ALD method and apparatus

ABSTRACT

A method and an apparatus for executing efficient and cost-effective Atomic Layer Deposition (ALD) at low temperatures are presented. ALD films such as oxides and nitrides are produced at low temperatures under controllable and mild oxidizing conditions over substrates and devices that are moisture- and oxygen-sensitive. ALD films, such as oxides, nitrides, semiconductors and metals, are efficiently and cost-effectively deposited from conventional metal precursors and activated nonmetal sources. Additionally, substrate preparation methods for optimized ALD are disclosed.

RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 10/384,504 filed Mar. 7, 2003, now U.S. Pat. No. 7,250,083,which claims the benefit of U.S. Provisional Patent Application No.60/362,870, filed Mar. 8, 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of integrated circuit fabrication,and more particularly to methods and apparati for improving atomic layerdeposition and other chemical reaction techniques.

2. Description of Prior Art

Thin film deposition is common in the fabrication of semiconductordevices and many other useful devices. Chemical vapor deposition (CVD)techniques utilize chemically reactive molecules that react on asubstrate to deposit a desired film. Reactants in CVD processes comprisevolatile molecules that can be practically delivered, in the gas phase,to react on the substrate to deposit a desired film.

Conventional CVD is practiced in the art by a variety of techniques.Desired thin film properties and cost-effective operational parametersinfluence the choice of equipment, precursor composition, pressurerange, temperature, and other variables. Common to most CVD techniquesis the application of a well-controlled flux of one or more molecularprecursors into the CVD reactor. A substrate is kept at awell-controlled temperature under well-controlled pressure conditions topromote chemical reaction between the molecular precursors concurrentwith efficient desorption of by-products. The chemical reaction isallowed to proceed to deposit the desired thin film with a desired filmthickness.

Optimum CVD performance directly correlates with the ability to achieveand sustain steady-state conditions of flux, temperature, and pressurethroughout the process, in which unavoidable transients are suppressedor minimized. CVD has provided uniform and conformal coatings withreproducible thickness and exceptional quality.

Nevertheless, as device density increases and device geometry becomesmore complicated in integrated circuit devices, the need for thinnerfilms with superior conformal coating properties has approached thelimits of conventional CVD techniques and new techniques are needed. Anemerging variant of CVD, atomic layer deposition (“ALD”) offers superiorthickness control and conformality for advanced thin film deposition.

ALD is practiced by dividing conventional thin-film deposition processesinto single atomic layer deposition steps that are self-terminating anddeposit precisely one atomic layer when conducted up to or beyondself-termination exposure times. An atomic layer typically equals about0.1 molecular monolayer to 0.5 molecular monolayer. The deposition of anatomic layer is the outcome of a chemical reaction between a reactivemolecular precursor and the substrate. In each separate ALDreaction-deposition step, the net reaction deposits the desired atomiclayer and eliminates the “extra” atoms originally included in themolecular precursor.

In ALD applications, typically two molecular precursors are introducedinto the ALD reactor in separate stages. For example, a metal precursormolecule, ML_(x), comprises a metal element, M (e.g., M=Al, W, Ta, andSi), that is bonded to atomic or molecular ligands, L. The metalprecursor reacts with the substrate. This ALD reaction occurs only ifthe substrate surface is prepared to react directly with the molecularprecursor. For example, the substrate surface typically is prepared toinclude hydrogen-containing ligands, AH, that are reactive with themetal precursor. The gaseous precursor molecule effectively reacts withall the ligands on the substrate surface, resulting in deposition of anatomic layer of the metal: substrate −AH+ML_(x)→substrate −AML_(x−1)+HL,where HL is a reaction by-product. During the reaction, the initialsurface ligands, AH, are consumed, and the surface becomes covered withL ligands, which cannot further react with metal precursor ML_(x).Therefore, the reaction self-terminates, or “saturates”, when all theinitial AH-ligands on the surface are replaced with AML_(x−1) species.The resulting substrate-AML_(x−1) surface is an ALD intermediatesurface, which is essentially covered with the L ligands.

The reaction stage is typically followed by an inert-gas purge stagethat eliminates the metal precursor from the chamber prior to theseparate introduction of the other precursor.

A second molecular precursor then is used to restore the surfacereactivity of the substrate towards the metal precursor. This is done,for example, by removing the L ligands and redepositing AH ligands. Inthis case, the second precursor typically comprises the desired (usuallynonmetallic) element A (i.e., O, N, S), and hydrogen (i.e., H₂O, NH₃,H₂S). The reaction, substrate −ML+AH_(y)→substrate −M −AH+HL, (here, forthe sake of simplicity, the chemical reactions are not balanced)converts the surface back to being AH-covered. The desired additionalelement, A, is incorporated into the film and the undesired ligands, L,are eliminated as volatile by-product. Once again, the reaction consumesthe reactive sites (this time, the L-terminated sites) andself-terminates (saturates) when the reactive sites on the substrate areentirely depleted. A different, second ALD intermediate surface isthereby created. In the simple example given here, the secondintermediate ALD surface is similar to the initial surface, where theinitial surface represents the surface prior to the introduction of themetal precursor.

Typically, the second molecular precursor then is removed from thedeposition chamber by flowing inert purge-gas in a second purge stage.

This sequence of surface reactions and precursor-removal that restoresthe substrate surface to its initial reactive state is a typical ALDdeposition cycle. Restoration of the substrate to its initial conditionis a key aspect of ALD. It implies that films can be layered down inequal metered sequences that are all identical in chemical kinetics,deposition per cycle, composition, and thickness. Self-saturatingsurface reactions make ALD insensitive to transport nonuniformity. Thistransport nonuniformity may pertain either to the engineering and thelimitations of the flow system or could be related to surface topography(i.e., deposition into three-dimensional, high-aspect ratio structures).Nonuniform flux of chemicals can only result in different completiontimes at different areas. However, if each of the reactions is allowedto complete on the entire substrate surface, the different completionkinetics bear no penalty. This is because the areas that are first tocomplete the reaction self-terminate the reaction, while the rest of thearea on the surface is able to complete the reaction, self-terminate,and essentially catch up.

Efficient practice of ALD requires an apparatus capable of changing theflux of chemicals from ML_(x) into AH_(y) abruptly and fast.Furthermore, the apparatus must be able to carry this sequencingefficiently and reliably for many cycles to facilitate cost-effectivecoating of many substrates. Typically, an ALD process deposits about 0.1nanometer (nm) of a film per ALD cycle. A useful and economicallyfeasible cycle time must accommodate a thickness in a range of aboutfrom 3 nm to 30 nm for most semiconductor applications, and even thickerfilms for other applications. Industry throughput standards dictate thatsubstrates be processed in 2 minutes to 3 minutes, which means that ALDcycle times must be in a range of about from 0.6 seconds to 6 seconds.Multiple technical challenges have so far prevented cost-effectiveimplementation of ALD systems and methods for manufacturing ofsemiconductor devices and other devices.

Generally, an ALD process requires alternating in sequence the flux ofchemicals to the substrate. A representative ALD process, as discussedabove, requires four different operational stages:

1. ML_(x) reaction;

2. ML_(x) purge;

3. AH_(y) reaction; and

4. AH_(y) purge.

Given the need for short cycle times, chemical delivery systems suitablefor use in ALD must be able to alternate incoming molecular precursorflows and purges with sub-second response times. Also, if significantflow nonuniformities exist, these can be overcome through theself-terminating nature of the chemical reactions by increasing thereaction-stage time to the time dictated by areas that are exposed tothe smallest flux. Nevertheless, this necessarily degrades throughputsince cycle times increase correspondingly.

In order to minimize the time that an ALD reaction needs to reachself-termination, at any given reaction temperature, the flux ofchemicals into the ALD reactor must be maximized. In order to maximizethe flux of chemicals into the ALD reactor, it is advantageous tointroduce the molecular precursors into the ALD reactor with minimumdilution of inert gas and at high pressures. On the other hand, the needto achieve low short cycle times requires the rapid removal of thesemolecular precursors from the ALD reactor. Rapid removal in turndictates that gas residence time in the ALD reactor be minimized. Gasresidence times, τ, are proportional to the volume of the reactor, V,the pressure, P, in the ALD reactor, and the inverse of the flow, Q,τ=VP/Q. Accordingly, lowering pressure (P) in the ALD reactorfacilitates low gas residence times and increases the speed of removal(purge) of chemical precursor from the ALD reactor. In contrast,minimizing the ALD reaction time requires maximizing the flux ofchemical precursors into the ALD reactor through the use of a highpressure within the ALD reactor. In addition, both gas residence timeand chemical usage efficiency are inversely proportional to the flow.Thus, while lowering flow will increase efficiency, it will alsoincrease gas residence time.

Conventional ALD apparati have struggled with the trade-off between theneed to shorten reaction times and improve chemical utilizationefficiency, and, on the other hand, the need to minimize purge-gasresidence and chemical removal times. Certain ALD systems of the priorart contain chemical delivery manifolds using synchronized actuation ofmultiple valves. In such systems, satisfactory elimination of flowexcursions is impossible because valve actuation with perfectsynchronization is itself practically impossible. As a result, theinevitable flow excursions are notorious for generating a backflow ofgas that leads to adverse chemical mixing. Improved methods and systemsof ALD using synchronous modulation of flow and draw (“SMFD”) aredisclosed in co-owned and copending U.S. patent application Ser. No.10/347,575, filed Jan. 17, 2003, which is hereby incorporated byreference.

Practical implementation of conventional ALD in commercial manufacturingapplications is also limited by a scarcity of suitable chemicalsequences, for example, an ML_(x) and AH_(y) sequence (and sometimes bysequences requiring more than two chemicals), that enable the desireddeposition with adequate speed and with adequate results. Chemicalsequences suitable for conventional ALD are not generic. ALD precursorsshould be stable at the reaction temperature. Self-decomposition of ALDprecursors at the reaction temperature prevents self-limitation, orsaturation. ALD precursors should react efficiently with theintermediate surface that is created by the previous chemical reactionin an ALD cycle. For example, ML_(x) molecules should react efficientlywith the surface terminated with AH species. If the reactions are notefficient, reaction times must be extended to allow for the reactions tooccur. Increasing reaction times limits the throughput that can beachieved. In addition, unreacted ligands, for example, the −AH and −MLligands, can degrade the purity of a film by inclusion of undesiredelements into the film, such as H and the elements composing the ligandL in the above. Furthermore, a molecular ALD precursor, such as ML_(x),should react only with some of their ligands, while other ligands shouldstay attached to the surface. For example, −ML should saturate thesurface in a self-terminating reaction to serve effectively as thereactive site on the immediate surface available to react with the othermolecular precursor, for example, AH_(y). Reaction by-products should bevolatile. For example, the HL reaction by-product, which evolves bothfrom the reaction of AH_(y) on −ML surfaces and from the reaction ofML_(x) on −AH surfaces, must be volatile. Finally, the surface speciesthat are left on an intermediate surface following the completion andself-termination of ALD reactions should be stable, with no or minimizeddesorption during the time that is practically necessary to remove theexcess precursor and reaction by-products and the time that it takes tocomplete the next surface reaction in sequence. For example, the −MLsurface termination sites should be stable during the time that it takesto sweep the ML_(x) molecules out of the reaction chamber and the timenecessary for the next reaction with AH_(y) to complete.

These requirements for ALD precursor selection (e.g., pairs, triplets)impose limitations on the films that can be produced inmanufacturing-grade ALD processes, due to the limitations on reactionrates and film purity caused by chemical sequences that do not meetthese requirements. Accordingly, although many different types of filmshave been deposited using ALD processes conducted in research settings,very few of these films (and related processes) are suitable for use incommercial ALD manufacturing. Unfortunately, the limited number of filmssuitable for use in commercial ALD manufacturing applications does notinclude many of the films having potential commercial importance. Forexample, an adequate ALD precursor combination has not been found in theprior art for single-element metal and semiconductor films needed forsemiconductor applications, such as titanium, tantalum, copper, silicon,and tungsten. Likewise, most nitride films, such as TiN, TaN_(x),WN_(x), and Si₃N₄, have not been demonstrated withprecursor-combinations that are adequate for cost-effective production.Also, many dielectric materials that are desired in the manufacture ofsemiconductor and other devices have not been demonstrated with adequateprecursor combinations. Accordingly, there is a need to develop agreater variety of precursor combinations that are suitable forcommercial ALD manufacturing applications.

In addition to the aforementioned limitations, ALD has another seriousfundamental limitation. Unlike CVD reactions (usually steady-state) thatare continuous and non-saturating, ALD reactions follow kinetics ofmolecule-surface interaction. The kinetics of molecule-surface reactionsdepend on the individual reaction rate between a molecular precursor anda surface reactive site and on the number of available reactive sites.As the reaction proceeds to completion, the surface is converted frombeing reactive to non-reactive. As a result, the actual process rate isslowing down during the deposition. Accordingly, ALD completion rates,dN/dt, are proportional to the number of reactive sites, dN/dt=−kN,where N is the number of reactive sites and k is the (single site)reaction rate. Elimination of the reactive sites for reaction follows anexponential time dependence N(t)=N₀exp(−kt). Accordingly, the“self-terminating” reactions essentially never self-terminate (as theywould require an infinite time to terminate because the rate isexponentially decreasing). This fundamental property of molecule-surfacekinetics was named after the scientist Langmuir, and is well known inthe art of surface science. The limitations of Langmuirian kineticspresent a significant limitation on overall throughput in conventionalALD.

As noted above, the limitations described by Langmuirian kineticsdictate that the surface is never “completely” reacted. If the surfaceis not completely reacted, there are necessarily leftover undesiredelements in the film. For example, if an ML_(x) reaction does nottotally consume the surface −AH sites, then the film incorporates H.Likewise, if the AH_(y) reaction is not carried to completion, undesiredL-incorporation results. The quality of a film depends on impuritylevels. Thus, ALD suffers from a throughput-quality tradeoff. Namely, toachieve greater throughput, it is generally assumed that quality must besacrificed, and vice-versa. This throughput-quality tradeoff is ofparticular concern because it carries an exponential throughput penaltyto attain a linear reduction of impurity levels.

Most critical applications of ALD films, particularly of semiconductorfilms, include stringent specifications regarding impurity levels.Accordingly, to achieve low impurity levels, ALD reactions typicallymust be conducted beyond 99% saturation. As noted above, however,Langmuirian kinetics dictate that conducting an ALD reaction up to orbeyond 99% saturation typically causes a serious reduction inthroughput.

Elevating ALD process temperatures potentially overcomes the limitationsposed by Langmuirian kinetics since ALD reactions are thermallyactivated. Nevertheless, in most cases, ALD process temperatures arepractically limited by one or more of the following factors: 1) devicemanufacturing integration becomes more difficult at increased processtemperatures; 2) instability of surface ligands and molecular precursorsgenerally increases with process temperature; and 3) deposition percycle inherently decreases with increased process temperature for mostknown ALD processes, thus resulting in the need to run more cycles todeposit the film up to the target thickness. As a result, many specificALD precursor combinations and potential ALD films are renderedinadequate for cost-effective commercial ALD manufacturing applications.Accordingly, there is a need for ALD methods and apparati that enable ageneric approach for ALD implementations, and that allow fabrication ofa larger range of ALD films at commercially feasible throughput andquality levels. Likewise, there is a need for ALD methods and apparatithat can surmount the Langmuirian limitations and enhance reactionkinetics without sacrificing film purity.

Despite the limitations of conventional ALD, ALD films have thepotential to provide a number of commercial manufacturing advantages.For example, ALD films have unique pinhole free and low stressadvantages. Accordingly, ALD films are ideal for device passivation andencapsulation applications. Much thinner encapsulation films can berealized by ALD than with conventional encapsulation processes. Suchthinner encapsulation films are advantageous for minimized alteration ofdevice performance. For example, it is desirable to encapsulate displayand optical devices by very thin films that minimize impact on lightoutput. However, material and process constraints of many devices limitmany passivation and encapsulation techniques for such devices toprocess temperatures not exceeding 200° C., and sometimes to less than100° C. In addition, some display and optical devices, for example,Organic Light Emitting Diode (OLED) display devices, are extremelysensitive to moisture and oxidizing conditions. The organic materialscommonly used in OLEDs are particularly susceptible to damage caused byexposure to the ambient atmosphere, as well as to reactions of organiccompounds with electrode materials. Furthermore, the metals typicallyutilized as OLED cathodes are highly reactive with oxygen and water andmay be negatively affected by oxidation. OLED device encapsulation andprotection from moisture and oxygen is currently accomplished by glasswindows and vacuum sealing techniques that are costly and cumbersome.Accordingly, there is a need to develop a commercially feasible thinfilm encapsulation method and apparatus for use in OLED manufacturingthat meets the above-mentioned needs.

In particular, there is a need for ALD methods with a generic approachthat can increase reaction rates, that are fast and efficient even atlow temperatures, and that allow flexibility in the choice of metal ALDprecursors.

SUMMARY OF THE INVENTION

The present invention helps to solve some of the problems discussedabove by providing systems, methods, and compositions for effecting achemical treatment of a substrate.

A method in accordance with the invention includes a continuous,non-saturating surface chemical reaction, referred to herein with theterm “catalyzing reaction”. A catalyzing reaction in accordance with theinvention does not, by itself, deposit solid material on the surface. Acatalyzing reaction requires two or more reactive chemicals, referred toherein as “catalyzing reactants”, that react with each other, preferablyvigorously, to produce a stable volatile by-product molecule and anunstable surface-adsorbed intermediate reactive molecular fragment. Acatalyzing reaction is thermodynamically driven and is irreversible byvirtue of volatilization of the stable by-product. The reactivemolecular fragments generated in catalyzing reactions generally form asadsorbed radical species. These adsorbed reactive molecular fragmentsare atomic or molecular sections, or both. Nevertheless, when thesurface contains reactive sites, a reactive fragment reacts with areactive site in a fragment-surface reaction, typically producing avolatile surface by-product or being incorporated into a growing film,or both. Thus, a catalyzing reaction generally proceeds (cascades) fromcatalyzing reactants to a final volatile species from both thecatalyzing reaction and from the reactive sites on the surface.

Catalyzing reactions are distinctively continuous. Nevertheless, in mostmethods including a continuous catalyzing reaction in accordance withthe invention, the catalyzing reaction is part of a process at asubstrate having a saturating nature, such as an ALD reaction stage, asurface treatment step, or a surface cleaning step. Therefore,catalyzing reactions are uniquely different from saturating ALD orsubstrate treatment processes of the prior art. When a saturatingprocess that is driven by a continuous catalyzing reaction in accordancewith the invention reaches saturation, the catalyzing reactions possessan additional unique characteristic; namely, they have a non-damagingpath for complete volatilization of all parts of the catalyzingreactants. While saturating processes are practically implemented onlyapproaching saturation (since ideal saturation requires infinite time),they are clearly converging. In contrast, a catalyzing reaction inaccordance with the invention continues as long as the correspondingcatalyzing reactants are present.

Catalyzing surface reactions (CSR) can serve as a source for hydrogenatoms, as well as other reactive species, that are necessary for thenonmetal ALD reaction. In this respect, a chemical process is enhancedby the addition of one or several continuous chemical reactions that arecapable of producing intermediate reactive molecular fragments. Thesereactive intermediates further react in the chemical process. Since thesole purpose of these additional side-reactions is to produce reactantsfor the original process, they are referred to as Catalyzing Reactionsfor Induced Surface Process (CRISP) in this application. CRISPs aredesigned to provide a volatilization path for adsorbed reactive specieswhen the surface reactive sites are depleted. Accordingly, CRISPs arerobust and can be carried excessively beyond saturation to ensurereproducible and satisfactory results.

This specification discloses methods and systems for achieving theeffects of reactive radical species without the need to generate anddeliver these reactive species from remote locations. Accordingly, metalALD can be done effectively. ALD of compound films also can beimplemented with these methods. In addition, surfaces of silicon, metal,and metal nitride can be effectively cleaned. In another extension ofthe technique, clean surfaces of metal and semiconductor substrates areterminated with a monolayer of H, OH, and NH surface species that isadvantageous for the growth of ALD films on these surfaces withreproducible results.

It is the primary objective of the present invention to provide acost-effective method and apparatus to practice ALD at low temperatures.It is a further objective of the invention to provide an efficient ALDprocess that is capable of preparing intermediate ALD surfaces forreaction with metal precursors, therefore enabling ALD. It is anadditional objective of the invention to efficiently prepareintermediate ALD surfaces for reaction with metal precursors undermildly oxidizing and moisture free conditions.

Still another objective of the invention is to provide a method andapparatus for ALD film growth over temperature-sensitive devices. It isalso the objective of the invention to produce protective ALD films oversubstrates that are sensitive to moisture and oxidizing environmentswithout deteriorating device performance. It is yet another objective ofthe invention to provide damage-free encapsulation of OLED displaydevices.

It is also the objective of the invention to provide a generic methodand processes that can substitute for the usage of non-metal ALDprecursors, wherein these processes are far more efficient and far lessdamaging to sensitive substrates. It is yet another objective of theinvention to provide substrate preparation for ALD.

In one aspect, a CRISP method in accordance with the invention includes:introducing a first catalyzing reactant into a reaction chamber, andintroducing a second catalyzing reactant into the reaction chamber,wherein the first catalyzing reactant and the second catalyzing reactantreact in a catalyzing reaction, the catalyzing reaction is continuousand non-saturating, and the catalyzing reaction generates a volatileby-product and an intermediate reactive molecular fragment. In anotheraspect of the invention, the intermediate reactive molecular fragmentreacts with an intermediate ALD surface in a saturating fragment-surfacereaction.

In another aspect of the invention, a CRISP method often includes morethan two catalyzing reactants, and the plurality of catalyzing reactantsreacts in a catalyzing reaction as described above.

An ALD method in accordance with the invention includes an ALD cyclecomprising a saturating chemical dosage stage and a saturating CRISPstage, which includes a CRISP method as outlined above. In anotheraspect of the invention, an ALD method in accordance with the inventionfurther includes conducting a deactivation or a purge stage after thesaturating fragment-surface reaction of the CRISP stage. In anotheraspect of the invention, the fragment-surface reaction generates asecond intermediate ALD surface. In another aspect of the invention, thesaturating chemical dosage stage includes: introducing a metal ALDprecursor that reacts with the second intermediate ALD surface in anactuating metal precursor-surface reaction, and the metalprecursor-surface reaction generates an intermediate ALD surface.

In another aspect of the invention, the metal precursor in thesaturating chemical dosage stage includes an atom selected from a groupincluding Al, Si, Ti, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Ru, In, Sn, Hf,Ta, and W. In this specification, the term “metal precursor” is usedgenerally to refer to a precursor for either a metal or a semiconductoratom.

In another aspect of the invention, an ALD method in accordance with theinvention is characterized in that the saturating CRISP stage furthercomprises varying a flow rate ratio of the catalyzing reactants duringthe CRISP stage to effect a plurality of catalyzing reactions insequence, such that each of the catalyzing reactions is continuous andnon-saturating, each of the catalyzing reactions generates a volatileby-product and an intermediate reactive molecular fragment, and eachintermediate reactive molecular fragment reacts with an intermediate ALDsurface in a fragment-surface reaction in a cascade of saturatingfragment-surface reactions. In another aspect of the invention, a flowrate ratio is varied so that a fragment-surface reaction substantiallysaturates before a succeeding fragment-surface reaction of the cascadeof fragment-surface reactions begins. In another aspect of theinvention, a first catalyzing reaction generates a first intermediatereactive molecular fragment, the first intermediate reactive molecularfragment reacts with a first intermediate ALD surface in a firstsaturating fragment-surface reaction, and the first fragment-surfacereaction generates a second intermediate ALD surface. In another aspectof the invention, a second catalyzing reaction generates a secondintermediate reactive molecular fragment, the second intermediatereactive molecular fragment reacts with the second intermediate ALDsurface in a second saturating fragment-surface reaction, and the secondfragment-surface reaction generates a third intermediate ALD surface.

In another aspect of the invention, in the CRISP stage, a finalfragment-surface reaction of the cascade of fragment-surface reactionsoccurs at an intermediate ALD surface and generates a final intermediateALD surface, and the saturating chemical dosage stage includesintroducing a metal ALD precursor that reacts with the finalintermediate ALD surface in a saturating metal precursor-surfacereaction that generates an initial intermediate ALD surface.

In another aspect of the invention, an ALD cycle in accordance with theinvention includes a saturating chemical dosage stage and a saturatingCRISP stage, and another ALD cycle comprises a saturating chemicaldosage stage and a saturating surface restoration stage. In stillanother aspect of the invention, an ALD cycle comprises a first-typesaturating chemical dosage stage and a corresponding first-typesaturating CRISP stage, and another ALD cycle comprises a second-typesaturating chemical dosage stage and a corresponding second-typesaturating CRISP stage. In another aspect of the invention, thefirst-type saturating chemical dosage stage includes introducing a firstmetal ALD precursor that reacts with a first intermediate ALD surface ina first saturating metal precursor-surface reaction, and the first metalprecursor-surface reaction generates a first-metal intermediate ALDsurface, and the corresponding first-type saturating CRISP stageterminates the substrate surface with a second intermediate ALD surface;and the second-type saturating chemical dosage stage includesintroducing a second metal ALD precursor that reacts with the secondintermediate ALD surface in a second saturating metal precursor-surfacereaction, the second metal precursor-surface reaction generates asecond-metal intermediate ALD surface, and the corresponding second-typesaturating CRISP stage terminates the substrate surface with anintermediate ALD surface. In still another aspect of the invention, thesecond-type saturating CRISP stage terminates the substrate surface withthe first intermediate ALD surface. In another aspect of the invention,the first intermediate ALD surface and the second intermediate ALDsurface are terminated substantially similarly. In another aspect of theinvention, the first-type saturating CRISP stage and the second-typesaturating CRISP stage are substantially similar.

In certain embodiments in accordance with the invention, an ALD cyclecomprises, in sequence, a saturating chemical dosage stage that includesflowing a chemical precursor gas through the reaction chamber at aselected first-dosage flow rate and at an independently selectedfirst-dosage pressure; then conducting a first purge stage by flowing afirst purge gas through the reaction chamber at a selected first purgeflow rate and at an independently selected first purge pressure; andthen in a CRISP stage, flowing the catalyzing reactants through thereaction chamber at a selected second-dosage flow rate and at anindependently selected second-dosage pressure. In another aspect of theinvention, the ALD cycle includes conducting a second purge stage aftera saturating fragment-surface reaction of the CRISP stage by flowing asecond purge gas through the reaction chamber at a selected second purgeflow rate and at an independently selected second purge pressure. Afurther embodiment in accordance with the invention includes initiatingthe saturating chemical dosage stage by initially flowing the chemicalprecursor gas at a first transient flow rate, the first transient flowrate being initially substantially greater than the first-dosage flowrate. In another aspect of the invention, the ALD cycle includesinitiating the CRISP stage by initially flowing the catalyzing reactantgases at second transient flow rates, the second transient flow ratesbeing initially substantially greater than the second-dosage flow rates.

In another aspect of the invention, certain embodiments in accordancewith the invention include utilizing SMFD techniques and systems, asdescribed in U.S. patent application Ser. No. 10/347,575. Generally, ina CRISP ALD method in accordance with the invention incorporating SMFDaspects, flowing a chemical precursor gas through the reaction chamberincludes controlling a chemical-dosage pressure in the reaction chamberby controlling a draw-control pressure in a draw control chamber locateddownstream from the reaction chamber. In a further aspect of theinvention, flowing catalyzing reactants through the reaction chambercomprises controlling a CRISP-pressure in the reaction chamber bycontrolling a draw-control pressure in a draw control chamber locateddownstream from the reaction chamber.

In another aspect of the invention, in a CRISP method in accordance withthe invention, the catalyzing reaction generates a plurality ofintermediate reactive molecular fragments. Frequently, the intermediatereactive molecular fragments comprise a hydrogen atom and a molecularfragment selected from a group including OH, NH, NH₂, SH, SeH, AsH, andAsH₂. In another aspect of the invention, controlling a flow rate ratioof the catalyzing reactants into the reaction chamber serves to controlrelative surface concentrations of the plurality of intermediatereactive molecular fragments, typically the surface concentrations ofhydrogen atoms and other molecular fragments.

An important aspect of a CRISP method in accordance with the inventionis that the thermodynamically-driven catalyzing CRISP reaction occurs atlow temperatures compared to reactions in conventional processes.Therefore, a chemical treatment process that includes a CRISP stage canbe conducted practically at a lower temperature than a process withoutCRISP. For example, a CRISP ALD method is typically performed at atemperature not exceeding 200° C., and frequently at a temperature notexceeding 100° C.

In another aspect of the invention, in an ALD process including CRISP,the plurality of catalyzing reactants comprises a first type ofcatalyzing reactant and a second type of catalyzing reactant; and thefirst type of catalyzing reactant is selected from a group including O₃,F₂, NF₃, ClF₃, HF, F₂O, FI, FNO, N₂F₂, F₂O₂, and F₄N₂, and the secondtype of catalyzing reactant is selected from a group including CH₄, CN,C₂H₈N₂, CH₅N, CH₆N₂, C₂H₂, C₂H₃N, C₂H₄, C₂H₄S, C₂H₅N, C₂H₆S, C₂H₆S₂,C₃H₆S, SiH₄, B₂H₆, Si₂H₆, SiH₂Cl₂, and PH₃.

In another aspect of the invention, an ALD CRISP process for depositingan oxide film is characterized in that the saturating CRISP stage isconducted without using H₂O.

In another aspect of the invention, at least one ALD cycle is conductedunder mild oxidizing conditions. In still another aspect of theinvention, at least one ALD cycle is conducted under mild oxidizingconditions, and at least one ALD cycle is conducted under strongoxidizing conditions.

In the general case of depositing a compound film MA by CRISP ALD, themetal precursor ML_(x) is deployed to react AH-terminated intermediatesurfaces to deposit a layer of M terminated with L ligands and selfsaturate. Following the removal of excess ML_(x), the AH_(y) precursoris substituted by a mixture of strong oxidizer, such as O₃ (ozone), anda hydrocarbon molecule, such as CH₄ (methane). Vigorous surface reactionbetween O₃ and CH₄ produces volatile CO₂ and CO molecules and providesan ample supply of adsorbed OH and H species. These species effectivelysubstitute L ligands with OH (A=O in this example) and desorb theligands as HL by-products. The net outcome parallels the results of theAH_(y) reaction. However, A, AH, and H are effectively broken down andsupplied at their most reactive form. Therefore, the reaction isefficient at low temperatures. In addition, surface exposure to strongoxidants is minimized by controlling the ratio between CH₄ (or otherhydrocarbons) and O₃. Finally, oxide growth is accomplished withoutexposing sensitive devices to H₂O.

Nitrogen-containing hydrocarbon molecules, such as CN (cyanide) andC₂H₈N₂ (dimethylhydrazine), can be used to incorporate nitrogen intogrowing films in order to deposit nitride or oxinitride compound films.CH₄ or other simple hydrocarbon molecules can be added to increasehydrogen concentrations on the surface and further suppress theresidence time of O₃ on the surface. Conditions may be set toefficiently eliminate oxygen by CO and CO₂ generation while the surfaceis supplied with ample concentrations of hydrogen and nitrogen.Thermodynamics dictate the coverage of surface NH_(x) species whileexcessive amounts of H and N recombine into volatile H₂, N₂, NH₃, andother possible nitrogen hydride compounds.

The ratio of C_(p)H_(q) to O₃ in the case of oxide deposition depends onthe sensitivity of the substrate to oxidizing conditions. The residencetime of O₃ and the relative abundance of surface OH and other oxidizingspecies inversely depends on the hydrocarbon:O₃ concentration ratio.Accordingly, sensitive substrates may dictate that the CRISP steps areexecuted under large hydrocarbon:O₃ concentration ratio conditions.However, CRISP reaction rates may slow down under mildly oxidizingconditions. A useful approach implements large hydrocarbon:O₃concentrations for the deposition of the first few layers of oxide and asmaller ratio for the deposition of bulk film. This approach providesmild exposure of sensitive substrates to oxidizing conditions, possiblyat the tradeoff of slower reaction rates, while the majority of the filmis executed under more oxidizing and higher throughput conditions thatare possible once the substrate is protected with continuous film.Recipe writing flexibility to tune oxidizing conditions is anotherstrength of CRISP ALD.

In addition to hydrocarbon-oxidant CRISP processes that are driven bythe stability and volatility of CO and CO₂, another approach implementsCRISP with hydride molecules, AH_(p), and fluorine containing molecules,DF_(q), where the creation of volatile AF_(p) fluoride molecules is thedriving force behind the CRISP. This approach may be preferred if usageof oxygen-containing catalyzing reactants is absolutely prohibited.Accordingly, two catalyzing reactants, AH_(p) and DF_(q), aredistributed over a substrate that is controlled at a sufficientlyelevated temperature. Upon impingement on the surface, the reactantsadsorbed and subsequently react:qAH_(p)+pDF_(q)→qAF_(p)+qH*+pD*,   (1)where H* and D* represent unstable intermediates that were created onthe surface. For example, B₂H₆ and NF₃ can facilitate growth of nitridefilms by providing highly reactive hydrogen and nitrogen. For example,TiN ALD may be facilitated by sequential exposures of TiCl₄ and B₂H₆/NF₃CRISP. In this case, efficient application of CRISP with, for example,B₂H₆ and NF₃, replaces the ALD reactant, NH₃, to facilitatesubstantially more efficient nonmetal reaction.

Central to the CRISP method is the usage of hydrocarbons, such as CH₄and C₂H₄, to react with strong oxidizing species such as O₃, oralternatively use hydride molecules such as SiH₄, B₂H₆, and PH₃, incombination with strong oxidants such as NF₃, ClF₃, and F₂ to generatestable and volatile CO, CO₂, or fluoride compounds such as SiF₄ or BF₃.The reaction between the above-mentioned hydrocarbon-oxidant or metalhydrides-fluoride molecules is extremely exothermic, being driven by thestability of CO, CO₂, or fluoride compounds. Accordingly, thesereactions are potentially explosive and require specially designedmethods and apparati to be conducted with good control. When used withadequate control, the combinations of hydrocarbon and strong oxidants ormetal hydride and fluoride molecules are extremely driven and efficient,and are capable of providing ample amounts of hydrogen, nitrogen, andother reactive species at the exact point of use, i.e., the substrate.

CRISPs also enable eliminating the use of AH_(y) precursors. Theseprecursors can persistently adsorb on most surfaces, making themnotorious for outgassing. Accordingly, CRISP substitutions of AH_(y)molecules are substantially easier to remove from ALD reactors. In manyinstances, removal of CRISP reactants may not require an inert gas purgestep. Rather, the flow of the oxidant, for example, O₃, may beterminated shortly prior to the termination of the hydrocarbon flow andthe CRISP processes will decay as the O₃ (and other surface reactivespecies) recombine and desorb from all surfaces, while theO₃/hydrocarbon gas in the ALD reactor is replaced by hydrocarbon only.This short deactivation step further enhances the final throughput ofCRISP ALD processes.

CRISP implementation to provide efficient ALD reactions can be carriedin one step or in multiple cascading steps. For example, a firstintermediate surface, covered with L ligands from the metal precursor,as described above, can be converted into an OH covered surface, for thedeposition of oxide films with a single CRISP step where the catalyzingreaction provides hydrogen to volatilize the L ligands and both hydrogenand oxygen to generate the surface OH ligand. Alternatively, a cascadeof two distinctively different CRISPs converts the surface to beH-covered with a first CRISP process, then with a second CRISP processconverts the surface from H-coverage to OH-coverage. Each one of the twoCRISP processes is carried to substantial saturation. A CRISP cascade isimplemented to speed up reaction and to improve the quality of the film.The second intermediate ALD surface, in this case the OH-terminatedsurface, is produced at the end of the final CRISP process within theCRISP cascade.

One of the unique advantages of ALD processes is the ability to produce,by design, complex film compositions and structures. Combination films,such as hafnium-aluminate and titanium-tantalum nitride, are depositedusing CRISP. Basically, these alloy or nanolaminate films are depositedby combining a variety of ALD processes that are used to deposit theindividual ingredient films. For example, hafnium-aluminate films with avariety of combinations are implemented by alternating the ALD processesfor aluminum oxide and hafnium oxide. As an obvious extension of thisinvention, CRISP ALD processes are combined with conventional ALDprocesses and/or other CRISP ALD processes to produce combination orcomposite ALD films.

Substrate preparation for ALD can significantly impact film growth anddevice performance. CRISP-based substrate preparation removes residualcontamination and oxide from all types of surfaces by providing atomichydrogen adsorbates on the surface. In addition, surface activation forALD is accomplished by precise deposition of surface species, such asOH, NH, NH₂, SH, SeH, and AsH_(x).

When metastable oxidants such as O₃ are being used, flow of CRISPreactants should compete with the rate of O₃ depletion. In the pressurerange that is useful for ALD (100 mTorr to 1000 mTorr), the metastablespecies decay mainly by surface recombination. Surface recombinationefficiencies of O₃ are rather low, making it a convenient reactivespecies. However, under conditions of very low flow, O₃ residence timemay be longer than O₃ depletion time. Accordingly, flow of O₃ is bestadjusted for maximized efficiency by increasing the flow rates to makedepletion negligible.

Efficient CRISP ALD apparatus design provides separate delivery ofcatalyzing reactants. Gas phase reactions between catalyzing reactantsdo not affect the quality of films or increase equipment wear. However,given the short lifetime of hydrogen atoms, gas phase catalyzingreactions reduce the efficiency of CRISP processes. Other features of anefficient CRISP ALD apparatus are exemplified in the preferredembodiment description.

CRISP control is generally achieved by keeping one of the catalyzingreactants at low concentration. Accordingly, the rate of the reaction isdetermined by the concentration of the minority catalyzing chemical.This approach is also advantageous to suppress potential side reactionsthat may compete with the CRISP and for suppressing damage to thesubstrate.

In some applications, catalyzing reactions are applied to promote acontinuous process. In these cases, such as CVD or etching, a catalyticreaction in accordance with the invention is faster, typically 10 timesor more, than a chemical reaction involving the other CVD precursors.Also, catalyzing reactions have a path for complete volatilization ofall atoms originally contained in the catalyzing reactants. Accordingly,catalyzing reactions can be conducted in a continuous process, such asCVD, in an advantageous mode in which the catalyzing reaction iscontrolled to be substantially excessive. In this mode, a substantialfraction of the catalytic reactants volatilize without reacting with theconventional CVD precursor; therefore, the CRISP part of the CVD processis relatively flux independent. Accordingly, a CVD process can becontrolled by controlling the flux of fewer precursors, namely, theconventional CVD precursors. Preferably, the catalytic reaction ispractically independent of the presence of the conventional CVDprecursors, which improves the control of conformality, film quality,and pulse CVD mode.

A generalized CRISP method of treating a solid film on a substrateincludes introducing a plurality of catalyzing reactants into a reactionchamber containing the solid film, so that the catalyzing reactantsreact in a continuous and non-saturating catalyzing reaction thatgenerates a volatile by-product and an intermediate reactive molecularfragment, whereby the intermediate reactive molecular fragment reactswith the solid film in a fragment-film reaction, and further includescontrolling a temperature of the chemical film to control the treating.In certain embodiments, the intermediate reactive molecular fragmentcomprises hydrogen, and the hydrogen is incorporated into the chemicalfilm during the fragment-film reaction. In other embodiments, theintermediate reactive molecular fragment comprises a hydrogen atom, andthe hydrogen improves the interface between the solid film and thesubstrate. In still other embodiments of the invention, the intermediatereactive molecular fragment comprises a hydrogen atom, and the hydrogenatom removes an in-film impurity. Examples of an in-film impurityremoved by a CRISP method in accordance with the invention include F, O,OH, Cl, and C. In another example of a film treatment utilizing a CRISPmethod, the intermediate reactive molecular fragment comprises a dopantatom, and the dopant atom is incorporated into the chemical film duringthe fragment-film reaction. Examples of a dopant atom are B and P. Inother embodiments of the invention, the treating comprises annealing thechemical film.

A method using CRISP is also utilized for activating a surface of asubstrate. An example of such a method includes exposing the surface toa gas mixture comprising catalyzing reactants selected from a group ofreactant combinations including O₃/hydrocarbon, hydride/oxyfluoride,O₃/nitrogen-containing-hydrocarbon, hydride/amine-fluoride, andO₃/sulfur-containing-hydrocarbon to effect surface hydroxylation. Amethod for activating a surface is useful, for example, for surfaceshaving a surface termination such as an oxide, a nitride, or a sulfidebefore activation. A CRISP activation method is utilized, for example,prior to deposition of an ALD layer comprising a material selected froma group including oxides, nitrides, sulfides, metals, and semiconductoratoms. Certain embodiments of an activation method using CRISP includeexposing the surface to a gas mixture comprising catalyzing reactantsselected from a group of reactant combinations including O₃/CH₄,O₃/C₂H₂, O₃/C₂H₄, SiH₄/F₂O, B₂H₆/F₂O, Si₂H₆/F₂O, SiH₂Cl₂/F₂O, PH₃/F₂O,SiH₄/F₂O₂, B₂H₆/F₂O₂, Si₂H₆/F₂O₂, SiH₂Cl₂/F₂O₂, and PH₃/F₂O₂.

An ALD apparatus in accordance with the invention preferably includesseparate delivery of at least some of the catalyzing reactants to avoida premature catalyzing reaction. Accordingly, an atomic layer deposition(ALD) apparatus preferably includes a first gas distribution chamber, asecond gas distribution chamber, and a reaction chamber disposeddownstream from the first and second gas distribution chambers. An SMFDALD apparatus further includes a first gas-distribution flow restrictionelement (FRE), providing fluidic communication between the first gasdistribution chamber and the reaction chamber, and a secondgas-distribution flow restriction element (FRE), providing fluidiccommunication between the second gas distribution chamber and thereaction chamber. Preferably, an ALD apparatus includes a draw controlchamber disposed downstream from the reaction chamber, areaction-chamber FRE in fluidic communication between the reactionchamber and the draw control chamber, a draw exhaust line in serialfluidic communication with the draw control chamber, and a draw-controlFRE in serial fluidic communication between the draw control chamber andthe draw exhaust line. In another aspect, an ALD apparatus in accordancewith the invention further includes a first catalyzing reactant sourcein fluid communication with, and disposed upstream from, the first gasdistribution chamber, and a second catalyzing reactant source in fluidcommunication with, and disposed upstream from, the second gasdistribution chamber. In another aspect, an ALD apparatus furtherincludes a draw-source shut-off valve to control a flow of draw-gasthrough the draw control chamber, and a draw-source-FRE in serialfluidic communication with the draw-source shut-off valve and the drawcontrol chamber. Preferably, an ALD apparatus further includes a drawgas introduction chamber (“DGIC”) in serial fluidic communicationbetween the reaction chamber and the draw control chamber, a draw-sourceshut-off valve to control a flow of draw gas into the DGIC, adraw-source-FRE in serial fluidic communication with the draw-sourceshut-off valve and the draw control chamber, and a DGIC-FRE locatedbetween the DGIC and the draw control chamber; wherein thereaction-chamber FRE is located between the process chamber and theDGIC. Certain embodiments further include an inert gas source in fluidiccommunication with a gas distribution chamber.

For low temperature applications, when extremely high doses of metalprecursor are necessary, design of an SMFD apparatus includes a uniquedownstream split of process gas. Thus, in another aspect of theinvention, an SMFD ALD apparatus allows splitting the draw (the flow outof an ALD reaction chamber) downstream of the draw control chamber. Suchan apparatus, therefore, further includes a plurality of draw-controlFREs and a plurality of after-draw control chambers. A typicalembodiment includes a first after-draw control chamber locateddownstream from the draw control chamber, a first draw-control FREdisposed between the draw control chamber and the first after-drawcontrol chamber, a first after-draw FRE in serial fluidic communicationbetween the first after-control chamber and the exhaust line, a secondafter-draw control chamber located downstream from the draw controlchamber, a second draw-control FRE disposed between the draw controlchamber and the second after-draw control chamber, and a secondafter-draw FRE in serial fluidic communication between the secondafter-control chamber and the exhaust line. As explained below, a flowof after-draw gas into an after-draw control chamber is utilized forcontrolling the relative pressures of after-draw control chambers andthereby controlling the distribution of process gas flow between theafter-draw control chambers. Certain embodiments of an ALD apparatusfurther comprise an abatement element disposed in an after-draw controlchamber.

ALD reactions are thermally activated and, therefore, slow down at lowtemperatures. Metal precursor reactions are typically very efficient.Accordingly, most metal precursors can be used with practical efficiencyat temperatures below 100° C. In conventional ALD processes of the priorart, the reactions of non-metal precursors, AH_(y), tend to berelatively inefficient and practically useless at temperatures below200° C. Therefore, in a method in accordance with the invention,conventionally used non-metal precursors such as H₂O, NH₃, and H₂S arereplaced with significantly more reactive precursors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 contains a process flow sheet of a CRISP ALD process inaccordance with the invention for deposition of an AlN/Al₂O₃ film stackover an ITO substrate;

FIG. 2 depicts schematically an intermediate surface during a CRISPstage of an ALD process in accordance with the present invention fordepositing AlN;

FIG. 3 contains a process flow sheet of a CRISP ALD process inaccordance with the invention for deposition of TiN film over a HfO₂substrate;

FIG. 4 contains a process flow sheet of a CRISP ALD process inaccordance with the invention for deposition of ZrO₂ film over a TiNsubstrate;

FIG. 5 contains a process flow sheet of a CRISP ALD process inaccordance with the invention for deposition of a ZnS film over an Al₂O₃substrate;

FIGS. 6A and 6B illustrate schematically a comparison of theintermediate steps of a conventional ALD (FIG. 6A) and a CRISP ALD (FIG.6B) in accordance with the invention occurring during conversion of an−MCl covered surface into a M−OH covered surface;

FIG. 7 contains a process flow sheet of a CRISP ALD process inaccordance with the invention for deposition of a metal film over anAl₂O₃ substrate;

FIG. 8 contains a schematic diagram of a CRISP SMFD ALD apparatus inaccordance with the invention;

FIG. 9 contains a schematic diagram of a CRISP SMFD ALD apparatus inaccordance with the invention for low temperature deposition of anAlN/Al₂O₃ film stack over a moisture- and oxygen-sensitive substrate;

FIG. 10 contains a schematic diagram of a CRISP SMFD ALD apparatus inaccordance with the invention for a metal hydride/fluoride-type CRISPALD;

FIG. 11 depicts a schematic top view of a dual-zone showerhead-designgas distribution device;

FIG. 12 depicts a schematic sectional view of the dual-zoneshowerhead-design gas distribution device of FIG. 11; and

FIG. 13 contains a schematic diagram of a CRISP SMFD ALD apparatus inaccordance with the invention with a split downstream and downstreammetal-precursor entrapment.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described herein with reference to FIGS. 1-13. For thesake of clarity, the same reference numerals are used in several figuresto refer to similar or identical components. It should be understoodthat the structures, methods, and systems depicted in schematic form inFIGS. 1-13 serve explanatory purposes and are not precise, comprehensivedepictions of actual structures, methods, and systems in accordance withthe invention. Furthermore, the embodiments described herein areexemplary and are not intended to limit the scope of the invention,which is defined in the claims below. Embodiments in accordance with theinvention are described below with reference mainly to systems andmethods for ALD deposition onto a single 200 mm wafer substrate. It isunderstood that the invention is useful on larger or smaller scales, andthat the dimensions and operating variables discussed below can bescaled up or down appropriately.

CRISP utilizing O₃ and CH₄ is illustrated in Equations 2 and 3:2O₃+CH₄→CO₂+4H+2O₂ and   (2)3O₃+CH₄→CO₂+3H+OH+3O₂.   (3)These chemical reactions are highly exothermic and are driven stronglyat any given temperature. For example, the enthalpy of formation for theprocess 2O₃+CH₄→CO₂ is Δ_(f)H°=−604.3 kJ/mole. On the other hand, theformation of free hydrogen atoms requires Δ_(f)H°=218 kJ/mole per atom.Therefore, on an inert surface, the reaction represented by Equation 2will proceed to produce hydrogen molecules (Δ_(f)H°=0):2O₃+CH₄→CO₂+2H₂+2O₂.   (4)

In one preferred embodiment in accordance with the invention, the CRISPmethod is implemented as an ALD step, for example, to react with a −MLterminated surface that is left following the completion of a ML_(x)exposure step. In this case, the reactive species follow thethermodynamic path to react with the surface L species producingvolatile HL by-products and terminating the surface with the mostthermodynamically preferred species, for example, OH. Accordingly, theprocess is described by Equation 5:3O₃+CH₄+substrate−ML→CO₂+substrate−M−OH+HL+H₂+3O₂.   (5)The enthalpy of formation of the CRISP ALD process represented bychemical Equation (5) is more exothermic, or more negative, than theenthalpy of the process represented by Equation 4, since the ALD part,substrate−ML+H₂O→substrate−M−OH+HL, is exothermic. Although the kineticsof the ALD reaction with H₂O is extremely slow at low temperature, thekinetics of the CRISP is fast and driven at any given temperature. Oncethe −ML surface is converted into −M−OH surface, the surface becomesinert for the particular CRISP process of Equations 2, 3, and 5, and theCRISP takes the path of Equation 4.

The ratio between O₃ and CH₄ affects the oxidizing conditions. LargeCH₄:O₃ ratios are useful for suppressing the formation of OH (and to alesser extent H₂O, H₂O₂) species. While it is not possible completely toavoid oxidizing conditions during growth of oxide films, tunability ofoxidizing conditions is useful for achieving growth with minimizeddamage to sensitive substrates. Alternatively, depositing several layersof nitride films provides a continuous protective barrier over sensitivesubstrates without exposing the substrate to an oxidizing environment.For example, dimethylhydrazine (C₂H₈N₂) replaces CH₄ as a hydrocarboncatalyzing reactant. A CRISP method in accordance with the inventiongenerates an intermediate reactive molecular fragment, such as H, NH, orNH₂, that is capable of converting an intermediate −ML surface into a−M−NH_(x) surface for the growth of an ALD metal nitride films. Forexample:4O₃+C₂H₈N₂+2substrate−ML→2CO₂+2substrate−M−NH+2HL+3H₂+4O₂  (6)Nitridation is enhanced by using higher ratios of N:H in the CRISPprocess, for example, by adding CN gas. The driving force of this CRISPprocess is the formation of stable CO₂, and the kinetics far exceed thekinetics achieved with conventional reactants, such as NH₃ or H₄N₂.

FIG. 1 contains an exemplary process flow sheet of a method inaccordance with the invention for deposition of AlN/Al₂O₃ on indium tinoxide (ITO). ITO represents a typical top surface layer of a topemitting OLED microdisplay device. Typically, the layers under an ITOfilm are sensitive to moisture and oxidizing conditions. Often, an ITOlayer, typically deposited by sputtering, is not pinhole-free and doesnot provide adequate protection for the underlying sensitive layers. Asa result, OLED devices often must be encapsulated by pinhole free filmsunder mildly oxidizing and moisture free conditions. The processtemperature cannot exceed 100° C. Usage of H₂O to facilitate the AH_(y)ALD dose step is precluded by the moisture sensitivity of the substrateand by slow reaction kinetics (at 100° C. and below). FIG. 1 contains aprocess flow sheet of an ALD method 100 in accordance with the inventionfor depositing a thin protective layer of AlN without exposing thesubstrate to oxidizing conditions (processes 106-112). The resultingthin layer of AlN provides additional protection to the sensitivesubstrate. An AlN layer is deposited to a thickness that is adequate toprotect sensitive OLED devices from the oxidizing conditions inprocesses 114-120 for growing an encapsulating Al₂O₃ film. Processes102, 104 are utilized to activate the ITO substrate. This activationterminates the substrate with surface species that can react with themetal precursor and initiate continuous film growth.

In FIG. 1, the substrate top layer of ITO is first exposed to the CRISPprocess at a high CH₄:O₃ concentration ratio. In a preferred embodiment,a CH₄:O₃ concentration ratio of 10:1 is sufficiently high. Accordingly,CRISP stage 102 converts strained Sn—O—Sn, Sn—O—In and In—O—In bridgesinto surface hydroxyl species. For purposes of example, Equation 7 showsthe above reaction with a strained In—O—Sn bridge taken as arepresentative example for an initial metoxane site (metal-O-metalbridge surface site):ITO−In−O−Sn−ITO+3O₃+CH₄→ITO−In−OH+ITO−Sn−OH+CO₂+3O₂+H₂*   (7)The CRISP catalyzing reaction is deactivated 104 for a short period oftime by terminating the flow of O₃. The reactive hydroxylatedintermediate ALD surface reacts in chemical dosage stage 106 withtrimethylaluminum (TMA, Al(CH₃)₃), resulting in deposition of Al, a—CH₃-terminated surface, and a volatile CH₄ by-product. See Equation 8:ITO−In−OH+ITO−Sn−OH+2Al(CH₃)₃→ITO−In−O−Al(CH₃)₂+ITO−Sn—O—Al(CH₃)₂+2CH₄*  (8)Excess TMA is removed during step 108 by inert gas purge. The—CH₃-terminated surface is further treated in CRISP stage 110 withcatalyzing reactant mixture O₃/C₂H₈N₂ to deposit nitrogen terminatedwith hydrogen and produce a CH₄ volatile by-product (see Equation 9):

$\begin{matrix} {\lbrack {- {{Al}( {CH}_{3} )}_{2}} \rbrack_{n} + {2n\; O_{3}} + {{n/2}\mspace{11mu} C_{2}H_{8}N_{2}}}arrow{\lbrack {- {AlNH}} \rbrack_{n} + {2n\;{CH}_{4}} + {n\;{CO}_{2}} + {2n\; O_{2}} + {{n/2}\mspace{11mu}{H_{2}.}}}  & (9)\end{matrix}$Following the completion of saturating CRISP stage 110 and deactivation112, TMA reacts with the amine (—NH) terminated intermediate ALD surfacein chemical dosage stage 106, as described in Equation 10. The sequenceof Equations 9 and 10 is repeated to grow AlN.[—AlNH]_(n)+nAl(CH₃)₃→[—NAl(CH₃)₂]_(n)+nCH₄.   (10)One of ordinary skill in the art appreciates that the terms in thesquare brackets in Equations 9 and 10 represent a surface polymericchain, since the nitrogen that is incorporated into the film linkssurface Al atoms together with Al—N—Al bridges where the hydrogen islocated on the bridging nitrogen atom. An illustration of the surface130 created by these reactions is shown in FIG. 2.

In deactivation stage 112, the flow of O₃ is terminated for a shortperiod of time sufficient for O₃ to decay and/or for the gas mixture ofO₃/C₂H₈N₂ to be replaced by C₂H₈N₂ only. A relatively short deactivation112 is usually sufficient and an inert gas purge is usually unnecessary.Steps 106-112 are repeated to deposit an AlN film with sufficientthickness to protect the sensitive device from the oxidizing conditionspresent in step 118.

Once a sufficient layer of AlN is deposited, the process flow proceedswith the deposition of Al₂O₃ following steps 114-120. TMA dosage stage114 is performed, followed by inert gas purge stage 116. The—CH₃-terminated intermediate ALD surface is exposed to catalyzingreactant mixture O₃/CH₄ in CRISP stage 118, to convert —CH₃ surfacespecies into —OH surface species, while producing CH₄ as volatileby-product. See Equations 11 and 12:[—Al(CH₃)_(2]) ₂+6O₃+2CH₄→HO−Al−O−Al−OH+4CH₄+2CO₂+H₂, and   (11)—Al—OH+Al(CH₃)₃→—Al—O—Al(CH₃)₂+CH₄.   (12)Subsequently, the flow of O₃ is terminated for a short period of time indeactivation stage 120 to deactivate the mixture of catalyzing CRISPreactants prior to the next TMA chemical dosage stage 114. The sequenceof ALD stages 114-120 is repeated to grow the desired encapsulationlayer thickness.

Alternative CRISP catalyzing reactions are used for AlN deposition. Inan alternative process, hydride molecules, such as SiH₄ or B₂H₆, areused to supply intermediate reactive molecular fragment hydrogen, whilea nitrogen fluoride compound, such as NF₃, F₂N or F₂N₂, suppliesnitrogen for an intermediate reactive molecular fragment. Thisparticular CRISP is extremely exothermic, being driven by the creationof volatile SiF₄ or BF₃, and provides ample amounts of adsorbed hydrogenand nitrogen. Since tin, indium or aluminum do not have volatilefluoride species, competition with possible fluorine etch paths does notexist, making the choice of catalyzing reactants and gas concentrationsrather flexible. Since all the catalyzing reactants are stable molecules(unlike when O₃ is employed), such CRISP stages are conducted at lowflow rates of catalyzing reactants to conserve usage of these chemicalsand reduce emission of hazardous waste. An embodiment of an apparatusdesign suitable for conducting a CRISP stage using a low flow rate of acatalyzing reactant is described below with reference to FIG. 8.

FIG. 3 depicts an exemplary process flow sheet of a method 150 inaccordance with the invention for deposition of metal nitride, inparticular, TiN, using an ALD cycle comprising sequential TiCl₄-dosageand B₂H₆/NF₃ CRISP stages. The metal precursor reaction is driven bygeneration of by-product HCl, and the catalyzing CRISP reaction isdriven by generation of its volatile by-product, BF₃. In the exemplarymethod of FIG. 3, the TiN film is deposited over HfO₂, which requireshydroxylation to facilitate initial growth. The HfO₂ surface isactivated by hydroxylation in CRISP stage 152 with a dilutecatalyzing-reactant mixture B₂H₆/F₂O (see Equation 13):Hf—O−Hf+B₂H₆+3F₂O→2Hf−OH+2BF₃+2H₂O.   (13)

CRISP stage 152 is followed by a purge with inert gas in stage 154. Thehydroxylated intermediate surface is exposed to metal precursor TiCl₄ insaturating chemical dosage stage 156 to deposit titanium and terminatethe surface with chlorine (see Equation 14):Hf—OH+TiCl₄→Hf—O—TiCl₃+HCl.   (14)

The volatile by-product of this reaction is HCl. Following purge stage158, the surface is exposed to saturating CRISP stage 160, to convertchlorine surface species into amine surface species and eliminatechlorine in HCl volatile by-product (see Equation 15):

$\begin{matrix} {\lbrack {- {TiCl}_{3}} \rbrack_{n} + {n\; B_{2}H_{6}} + {2n\;{NF}_{3}}}arrow{\lbrack {- {TiNH}} \rbrack_{n} + {2\;{BF}_{3}} + {n\; H_{2}} + {n\; H_{2}} + {{n/2}\mspace{11mu} N_{2}} + {3n\;{{HCl}.}}}  & (15)\end{matrix}$Following a purge stage 162 to eliminate the CRISP reactants, theamine-terminated intermediate ALD surface reacts with TiCl₄ (repeatstage 156) in the next ALD cycle (see Equation 16):[—TiNH]_(n)+nTiCl₄→[—TiN—TiCl₃]_(n)+nHCl.   (16)The sequence 156-162 is repeated to grow TiN.

Fluorine-based chemistry is useful for oxide growth using CRISP. Forexample, SiH₄ is used with fluorine oxide molecules such as F₂O or F₂O₂to replace H₂O in the deposition of oxide. Generation of SiF₄ volatileby-product makes these reactions extremely thermodynamically driven andefficient, enabling deposition of oxide films at low temperatures with ahigh SiH₄:F_(p)O_(q) concentration ratio. The resulting mild oxidationconditions in this embodiment are useful for low temperature depositionon sensitive substrates, for example, during OLED fabrication.

FIG. 4 displays a process flow sheet of an exemplary method 200 inaccordance with the invention for metal oxide deposition, namely, ZrO₂,using an ALD cycle comprising a saturating metal-precursor dosage stageincluding ZrCl₄ and a saturating CRISP stage including acatalyzing-reactant mixture SiH₄/F₂O. The saturatingmetal-precursor-surface reaction generates HCl by-product, and thecatalyzing CRISP reaction is driven by volatilization of SiF₄. In method200 of FIG. 4, the substrate is TiN and first CRISP stage 202 is used toreduce a native oxide TiO_(x) surface and to remove residual carbon byhydrogen exposure. In CRISP stage 204, titanium is terminated with aminespecies in preparation for ZrO₂ growth. Following the inert gas purgestage 206, the amine-terminated intermediate ALD surface reactants withZrCl₄ to deposit Zr and terminate the surface with chlorine species inmetal-precursor chemical dosage stage 208. The metal-precursor-surfacereaction is driven by the generation of volatile HCl. Followinginert-gas purge stage 210, catalyzing-reactant mixture SiH₄/F₂O reactswith the chlorinated intermediate surface in saturating CRISP stage 212and generates a hydroxylated intermediate surface. The reaction chamberis subsequently purged in purge stage 214. The sequence 208-214 isiterated to grow ZrO₂ film.

In other exemplary methods comprising CRISP ALD of silicon oxide ormetal oxide films, a chemical dosage stage includes general metalprecursors of the form M(OC_(p)H_(q))_(r), where M represents a metal orsemiconductor atom, and a saturating CRISP stage includes anO₃/C_(s)H_(t) catalyzing reactant mixture. For example, oxides ofsilicon or metal and the corresponding metal (or silicon) precursorsare:

SiO₂: Si(OC₂H₅)₄ (tetraethoxysilane), Si(OCH₃)₄ (tetramethoxysilane);

Ta₂O₅: Ta(OC₂H₅)₅ (tantalum (V) ethoxide);

ZrO₂: Zr(OC₂H₅)₄ (zirconium (IV) ethoxide), Zr((OC(CH₃)₃)₄ (Zirconiumt-butoxide; and

HfO₂: Hf(OC₂H₅)₄ (hafnium (IV) ethoxide), Hf((OC(CH₃)₃)₄ (Hafniumt-butoxide).

The above precursors are used in combination with CRISP stages includingcatalyzing reactants such as O₃/CH₄ or O₃/C₂H₂.

The following are some general equations for an exemplary process:

substrate − OH + M(O C_(p)H_(q))_(r) → substrate − O − M(OC_(p)H_(q))_(r − 1) + C_(p)H_(q)OH, and$ {{substrate} - O - M - {{OC}_{p}H_{q}} + O_{3} + {\frac{1}{2}{CH}_{4}}}arrow{{Substrate} - O - M - {OH} + {C_{p}H_{q + 1}} + O_{2} + {\frac{1}{2}{{CO}_{2}.}}} $For simplicity, the second equation illustrates the process ofhydroxylating a single —OC_(p)H_(q) group.

SPECIFIC EXAMPLES

SiO₂:

substrate − OH + Si(OC₂H₅)₄ → substarte − O − Si(OC₂H₅)₃ + C₂H₅OH, and$ {{substrate} - O - {Si} - {{OC}_{2}H_{5}} + O_{3} + {\frac{1}{2}{CH}_{4}}}arrow{{Substrate} - O - {Si} - {OH} + {C_{2}H_{6}} + O_{2} + {\frac{1}{2}{{CO}_{2}.}}} $

It should be understood that the “OH” surface species in the secondequation represents three such surface species that are formed on thesurface. Since generally there are three alkoxy groups for each siliconatom on the surface, O₃/CH₄ CRISP stage generates three surface —OHspecies. Two of these —OH species react with other —OH species fromother —Si(OH)₃ to form water and Si—O—Si (siloxane) bridges. Thesiloxane bridges create the SiO₂ bulk network bonding. The watermolecules are drawn off as water vapor. Volatile surface by-products ofthe fragment-surface reaction include ethanol (C₂H₅OH) and ethane(C₂H₆).

SiO₂:

substrate − OH + Si(OCH₃)₄ → substrate − O − Si(OCH₃)₃ + CH₃OH, and$ {{substrate} - O - {Si} - {OCH}_{3} + O_{3} + {\frac{1}{2}{CH}_{4}}}arrow{{Substrate} - O - {Si} - {OH} + {CH}_{4} + O_{2} + {\frac{1}{2}{{CO}_{2}.}}} $Ta₂O₅:

substrate − OH + Ta(OC₂H₅)₅ → substrate − O − Ta(OC₂H₅)₄ + C₂H₅OH, and$ {{substrate} - O - {Ta} - {{OC}_{2}H_{5}} + O_{3} + {\frac{1}{2}{CH}_{4}}}arrow{{Substrate} - O - {Ta} - {OH} + {C_{2}H_{6}} + O_{2} + {\frac{1}{2}{{CO}_{2}.}}} $

The possible reaction by-products also include ethanol, as well asethane.

ZrO₂:

substrate − OH + Zr(OC₂H₅)₄ → substrate − O − Zr(OC₂H₅)₃ + C₂H₅OH, and$ {{substrate} - O - {Zr} - {{OC}_{2}H_{5}} + O_{3} + {\frac{1}{2}{CH}_{4}}}arrow{{Substrate} - O - {Zr} - {OH} + {C_{2}H_{6}} + O_{2} + {\frac{1}{2}{{CO}_{2}.}}} $

The possible reaction by-products also include ethanol.

HfO₂:

substrate − OH + Hf(OC₂H₅)₄ → substrate − O − Hf(OC₂H₅)₃ + C₂H₅OH, and$ {{substrate} - O - {Hf} - {{OC}_{2}H_{5}} + O_{3} + {\frac{1}{2}{CH}_{4}}}arrow{{Substrate} - O - {Hf} - {OH} + {C_{2}H_{6}} + O_{2} + {\frac{1}{2}{{CO}_{2}.}}} $

The possible reaction by-products also include ethanol.

It is useful to represent such processes with three equations. Forexample:

SiO₂:

$ {{substrate} - {OH} + {{Si}( {{OC}_{2}H_{5}} )}_{4}}arrow{{substrate} - O - {{Si}( {{OC}_{2}H_{5}} )}_{3} + {C_{2}H_{5}{OH}}} , {\lbrack {{substrate} - O - {{Si}( {{- {OC}_{2}}H_{5}} )}_{3}} \rbrack_{n} + {3n\; O_{3}} + {\frac{3n}{2}{CH}_{4}}}arrow{\lbrack {{Substrate} - O - {{Si}( {- {OH}} )}_{3}} \rbrack_{n} + {3n\; C_{2}H_{6}} + {3n\; O_{2}} + {\frac{3n}{2}{CO}_{2}}} , {{and}\lbrack {{Substrate} - O - {{Si}( {- {OH}} )}_{3}} \rbrack}_{n}arrow{\lbrack {{Substrate} - O - {{Si}( {{- O} -} )}_{2} - {OH}} \rbrack_{n} + {2n\; H_{2}O}} ,$where the third equation in the set represents the process ofcondensation that creates the cross-linking bonds of the SiO₂ film. Twocross-linking bonds are generated per silicon atom derived from thetetraethoxysilane. It should be understood that the process describedabove is actually a three-dimensional process.

The exemplary methods described herein illustrate an importantcharacteristic of CRISP: instead of conducting a saturating reactionwith molecules, which results in slow processes, catalyzing reactantsreact in a catalyzing CRISP reaction to generate one or moreintermediate reactive molecular fragments, and the fragment or fragmentsreact more quickly at an intermediate surface.

An ALD method in accordance with the invention is suitable fordepositing a wide variety of metal-containing (andsemiconductor-atom-containing) layers on the surface of a substrate. Forexample, an ALD method for depositing a layer containing TiN includesthe metal precursor TiCl₄ in the saturating chemical dosage stage, and afirst catalyzing reactant SiH₄ and a second catalyzing reactant NF₃ inthe saturating CRISP stage. Another example is an ALD method fordepositing a layer comprising a ZrO₂ ALD film in which the metalprecursor in the saturating chemical dosage stage is selected from agroup including ZrCl₄ and Zr(O-t-C₄H₉)₄, a first catalyzing reactant inthe saturating CRISP stage is selected from a group including O₃ andB₂H₆, and a second catalyzing reactant in the saturating CRISP stage isselected from a group including C₂H₄, C₈H₁₀, CH₃OH, C₂H₅OH, i-C₃H₇OH,t-C₄H₉OH, and F₂O. A further example is an ALD method for depositing alayer comprising a HfO₂ ALD film in which the metal precursor in thesaturating chemical dosage stage is selected from a group includingHfCl₄ and Hf(O-t-C₄H₉)₄, a first catalyzing reactant in the saturatingCRISP stage is selected from a group including O₃ and B₂H₆, and a secondcatalyzing reactant in the saturating CRISP stage is selected from agroup including C₂H₄, C₈H₁₀, CH₃OH, C₂H₅OH, i-C₃H₇OH, t-C₄H₉OH, and F₂O.A further example is an ALD method for depositing a layer comprising aSiO₂ ALD in which the metal precursor in the saturating chemical dosagestage is selected from a group including Si(OC₂O₅)₄, SiCl₄, and SiH₂Cl₂,a first catalyzing reactant in the saturating CRISP stage is selectedfrom a group including O₃ and B₂H₆, and a second catalyzing reactant inthe saturating CRISP stage is selected from a group including C₂H₄,C₈H₁₀, CH₃OH, C₂H₅OH, i-C₃H₇OH, t-C₄H₉OH, and F₂O.

A further example is an ALD method for depositing a layer comprising aTa₂O₅ ALD film in which the metal precursor in the saturating chemicaldosage stage is selected from a group including Ta(OC₂O₅)₅ and TaCl₅, afirst catalyzing reactant in the saturating CRISP stage is selected froma group including O₃ and B₂H₆, and a second catalyzing reactant in thesaturating CRISP stage is selected from a group including C₂H₄, C₈H₁₀,CH₃OH, C₂H₅OH, i-C₃H₇OH, t-C₄H₉OH, and F₂O.

A further example is an ALD method for depositing a layer comprising acopper ALD film in which the metal precursor in the saturating chemicaldosage stage is selected from a group including Cu(tfac)₂ and Cu(hfac)₂,a first catalyzing reactant in the saturating CRISP stage is selectedfrom a group including SiH₄, SiH₂Cl₂, B₂H₆, Si₂H₆, C₈H₁₀, and CH₃OH, anda second catalyzing reactant in the saturating CRISP stage is selectedfrom a group including F₂, F₂O, NF₃, ClF₃, and O₃.

A further example is an ALD method for depositing a layer comprising a WALD film in which the metal precursor in the saturating chemical dosagestage is selected from a group including WF₆ and WCl₆, a firstcatalyzing reactant in the saturating CRISP stage is selected from agroup including SiH₄, SiH₂Cl₂, B₂H₆, Si₂H₆, C₈H₁₀, and CH₃OH, and asecond catalyzing reactant in the saturating CRISP stage is selectedfrom a group including F₂, F₂O, NF₃, ClF₃, and O₃.

A further example is an ALD method for depositing a layer comprising aMo ALD film in which the metal precursor in the saturating chemicaldosage stage is selected from a group including MoCl₅, a firstcatalyzing reactant in the saturating CRISP stage is selected from agroup including SiH₄, SiH₂Cl₂, B₂H₆, Si₂H₆, C₈H₁₀, and CH₃OH, and asecond catalyzing reactant in the saturating CRISP stage is selectedfrom a group including F₂, F₂O, NF₃, ClF₃, and O₃.

A further example is an ALD method for depositing a layer comprising aSi ALD film in which the metal precursor in the saturating chemicaldosage stage is selected from a group including Si(OC₂H₅)₅, SiH₂Cl₂,SiCl₄, SiH₄, and SiHCl₃, a first catalyzing reactant in the saturatingCRISP stage is selected from a group including SiH₄, SiH₂Cl₂, B₂H₆,Si₂H₆, C₈H₁₀, and CH₃OH, and a second catalyzing reactant in thesaturating CRISP stage is selected from a group including F₂, F₂O, NF₃,ClF₃, and O₃.

A further example is an ALD method for depositing a layer comprisingaluminum oxide (Al₂O₃) in which a metal precursor in the saturatingchemical dosage stage comprises trimethylaluminum, a first catalyzingreactant in the saturating CRISP stage comprises ozone (O₃), and asecond catalyzing reactant in the saturating CRISP stage comprises ahydrocarbon molecule selected from a group including methane (CH₄),C₂H₆, C₂H₄, and C₈H₆.

A further example is an ALD method for depositing a layer comprisingaluminum oxide (Al₂O₃) in which a metal precursor in the saturatingchemical dosage stage comprises trimethylaluminum, a first catalyzingreactant in the saturating CRISP stage comprises ozone (O₃), and asecond catalyzing reactant in the saturating CRISP stage comprises analcohol molecule.

As another example, a CRISP method is useful to deposit sulfide films.For example, an H₂S reaction is catalyzed by a CRISP-generated chlorinefragment to promote deposition of sulfur. Subsequently, a CRISP reducingstage is utilized to remove excessive sulfur down to a single layer thatis terminated with hydrogen. Chlorine is provided by mixing catalyzingreactants H₂S and SCl₂, or by the CRISP mixture of a catalyzing chloridereactant, such as SiCl₄, and a fluorine-containing catalyzing reactant,such as ClF₃. The catalyzing CRISP reactants accelerate (or catalyze)completion of a potentially slow process, such as the reaction ofmolecular H₂S with chlorine-terminated surfaces, by reacting in acatalyzing reaction to generate one or more intermediate reactivemolecular fragments. FIG. 5 contains a process flow sheet of anexemplary method 250 in accordance with the invention for depositingZnS. Similar methods are useful for depositing other compound materials,such as ZnSe. In exemplary method 250, a substrate comprising Al₂O₃ ishydroxylated in CRISP stage 252 using catalyzing reactants SiH₄ and F₂O.After purge stage 254, metal precursor ZnCl₂ is introduced into thereaction chamber in chemical dosage stage 256 to deposit Zn on thesubstrate surface. After purge stage 258, a sequence of catalyzingreactions is conducted by varying the flow rates of catalyzing reactantsduring CRISP stage 260/262. In substage 260, catalyzing reactants H₂S,SiCl₄ and ClF₃ are introduced into the reaction chamber in a flow rateratio of approximately 5:1:1 to deposit sulfur. In substage 262, excesssulfur is removed by introducing SiH₄ and F₂ into the reaction chamberin a flow rate ratio of approximately 5:1. The result of sequence260/262 is a cascade of fragment-surface reactions resulting in anintermediate ALD surface that reacts with the metal precursor ZnCl₂ inchemical dosage stage 256 after purge stage 264. An example of theflexibility of a method including CRISP in accordance with the inventionis that, while the catalyzing reactions and resulting fragment-surfacereactions of substages 260 and 262 occur sequentially, a similarcatalyzing effect may be achieved by combining substages 260 and 262into a single catalyzing reaction comprising H₂S, SiH₄, and ClF₃.

In another aspect, an ALD CRISP process includes conducting an initialALD cycle and further ALD cycles, wherein conducting the initial ALDcycle comprises: introducing a metal ALD precursor that reacts with aninitial ALD surface in an initial saturating metal precursor-surfacereaction to deposit a metal atom on the substrate, and the metalprecursor-surface reaction generates a first intermediate ALD surfacethat contains a ligand of the metal ALD precursor; and whereinconducting the initial ALD cycle further includes conducting an initialsaturating CRISP stage in which an intermediate reactive molecularfragment comprising atomic hydrogen reacts with the first intermediateALD surface in an initial saturating fragment-surface reaction, and theinitial saturating fragment-surface reaction generates a volatilesurface by-product containing a hydrated form of the metal precursorligand, thereby removing the metal precursor ligand from the substrate,and the initial saturating fragment-surface reaction terminates themetal with hydrogen, thereby generating a second intermediate ALDsurface; and wherein conducting a further ALD cycle comprises:introducing a metal ALD precursor that reacts with the hydrogen in thesecond intermediate ALD surface in a saturating metal-surface reactionto deposit a metal atom on the substrate, and the metal-surface reactiongenerates the first intermediate ALD surface, and the first intermediateALD surface comprises a ligand of the metal ALD precursor; and whereinconducting a further ALD cycle includes conducting a CRISP stage inwhich an intermediate reactive molecular fragment comprising atomichydrogen reacts with the first intermediate ALD surface in a saturatingfragment-surface reaction, and the saturating fragment-surface reactiongenerates a volatile surface by-product containing a hydrated form ofthe metal precursor ligand, thereby removing the metal precursor ligandfrom the substrate, and the saturating fragment-surface reactionterminates the metal with hydrogen, thereby generating a secondintermediate ALD surface.

FIG. 6A depicts a conventional ALD process using conventional H₂Oexposure. FIG. 6B depicts a saturating CRISP stage in an ALD method inaccordance with the invention. In both FIGS. 6A and 6B, a surfaceterminated with −MCl is converted into −MOH, and the process is drivenby the release of volatile HCl by-product. In FIG. 6A, the kinetics ofthe conventional process are dictated by several high-barrier factors.The surface 302 is exposed to H₂O and the first limiting factor isadsorption of H₂O over a surface terminated with Cl. This adsorptionprocess 305 is not efficient and creates a mediating adsorption statewith bond strength in the order of E_(a)˜20 kJ/mole. The adsorption doesnot greatly affect either the M—Cl or the H—OH bond strengths.Simultaneous breakage of these bonds is required to induce the ALDreaction. Accordingly, the barrier for the conventional ALD reaction 310shown in FIG. 6A is high (empirically typically higher than E_(r)˜100kJ/mole). Consequently, most adsorbed H₂O molecules desorb from thesurface and only a very small fraction reacts. The fraction of adsorbedmolecules that reacts scales exponentially with (E_(a)−E_(r))/RT.Accordingly, the combined process is highly thermally activated.Typically, AH_(y) reactions slow down more than three orders ofmagnitude when the temperature is reduced from 300° C. to 100° C.

In contrast, a CRISP stage is much less temperature dependent. As shownin FIG. 6B, instead of H₂O, a continuous, non-saturating catalyzingCRISP reaction generates a volatile by-product (not shown) andintermediate reactive molecular fragments OH and H that react with theintermediate MCl-terminated surface 322 in fragment-surface reactions325, 330. Hydrogen atoms adsorb strongly on the chlorine sites makingthe metal-chlorine bond weaker. The OH species attach strongly to themetal atoms and further weaken the metal-chlorine bond. As a result,adsorption and reaction energies are similar, E_(a)˜E_(r). Accordingly,the reaction path produces desired intermediate ALD surface 330 atspeeds orders of magnitude faster than in conventional ALD. Furthermore,the CRISP process 325, 330 is less temperature dependent.

Most common metal precursors adsorb on −AH terminated surfaces with anadsorption energy of 20 kJ/mole to 30 kJ/mole. The barrier for surfacereaction is on the order of 40 kJ/mole to 60 kJ/mole. Thus, the fractionof adsorbed molecules that reacts in a metal-precursor surface reactioncorresponding to the process of FIG. 6A is substantially higher than inthe case of conventional AH_(y) precursors, and thetemperature-dependence of the metal-precursor reaction is not as strong.Therefore, reaction rates at 300° C. are typically orders of magnitudefaster than reaction rates of conventional nonmetal precursors. Reactionrates of metal precursors typically slow down by a factor of only about10 when the process temperature is reduced from 300° C. to 100° C.

The reaction temperature of a fabrication method is typically dictatedby the application, such as in the case of encapsulation layers for OLEDdisplays. The thermal stability of surface species is also aconsideration. The coverage and stability of −AH species is important,since it has been determined to be a major factor affecting the amountof material deposited per ALD cycle in certain ALD processes. AHspecies, such as OH, NH, NH₂, and SH, typically desorb by a condensationmechanism. For example, surface OH species can produce one volatile H₂Omolecule and one surface M—O—M bridge site per two OH species.Thermodynamics dictate that, at any given temperature, the lowestsurface energy determines a given coverage of OH species. This coverageis stable and decays relatively slowly on the time scale of the ALDprocess. Therefore, intermediate OH-covered surfaces performsubstantially ideally in ALD.

Similarly, amine-terminated surfaces, −NH and −NH₂, exhibit substantialstability that enables ALD with close to ideal characteristics.Nevertheless, growth per cycle of nitride films is rather small,typically on the order of 10% of a monolayer in the typical temperaturerange of from 250° C. to 450° C., indicating that surface-stabilizationof amine species is substantially smaller than that of OH species.

Hydrogen terminations on elemental films from Group IVB (Si, C, Sn, Pb,Ge) are rather stable under typical processing temperatures in a rangeof 200° C. to 450° C. Similarly, hydrogen-termination on intermediatenonmetal surfaces of GaAs, InP, and other 3-5 and 2-6 type compoundsemiconductors are relatively stable. Hydrogen termination on metalsurfaces vary in stability, but desorb rapidly at temperatures higherthan 100° C.

Therefore, the stability of hydrogen species limits metal ALD methods torelatively low temperatures. For example, in Equation 17, hydrogendesorption from copper surfaces follows a second order kinetics:

$\begin{matrix}{{\frac{\mathbb{d}\theta}{\mathbb{d}t} = {{{- k}\;\theta^{2}} \approx {{- 3} \times 10^{11}{\exp( {- \frac{9300}{T}} )}}}},} & (17)\end{matrix}$where 0≦θ≦1 is the coverage of hydrogen relative to a fully coveredsurface of ˜1.5×10¹⁵ H/cm², and k is the second order desorption rate.Accordingly, hydrogen desorption is a concern during typical ALD purgeand dosage times at temperatures higher than 30° C. For example, at 80°C., an estimated ˜10% desorption of surface hydrogen will occur during aminimal 200 msec time period following a CRISP stage. Therefore, ALD ofcopper is generally restricted to very low temperatures. Certaincompromises of ALD ideality are tolerable to extend the temperaturerange. Nevertheless, in the case of copper, this extension can hardly gobeyond 100° C. Other metals of practical importance, such as Al, Ti, W,Mo, and Ta, require ALD deposition below 150° C.

ALD metal deposition carried at high temperatures (>200° C.) using aconventional, prior-art technique results in complete desorption ofhydrogen within time periods of about 10 msec, which practically exposesbare metal surfaces. In a subsequent dosage of metal precursor, atypical metal precursor is capable of irreversible dissociativechemisorption on the exposed metal surface. Dissociative chemisorptionover metallic surfaces, however, typically does not self terminate. Inparticular, exposing bare metallic surfaces to metal halide precursorstypically results in continuous growth of metal (and thereby in theformation of undesired porous films). In addition, bare metal surfacesare extremely sensitive to contamination from residual gas in an ALDapparatus.

An advantage of a CRISP ALD method is that a CRISP stage suitable forgenerating intermediate reactive hydrogen adsorbate can be conducted ata low temperature, for example, less than 100° C., thereby avoiding theproblem of hydrogen desorption characteristic of high-temperature ALD ofthe prior art. FIG. 7 contains a process flow sheet of an exemplarymethod 350 for depositing metal in a sequence of ML, exposures, followedby a hydrogen-generating CRISP stage. In method 350, Al₂O₃ ishydroxylated in CRISP stage 352, and after purge 354, exposed to a metalchloride precursor in chemical dosage stage 356. Following purge stage358, the chlorine species are reduced using SiH₄/ClF₃ catalyzingreactant mixture in CRISP stage 360. Following a short deactivationstage 362, the ALD cycle comprising stages 356-362 is repeated to growmetal film.

CRISP is also useful for preparing substrates for ALD. Both substratecleaning and activation require a well-controlled supply of reactiveatomic or molecular fragments on the surface. Unlike plasma techniques,where efficient supply of these reactive species to the surface withoutdamaging the substrate is difficult and typically not practical, CRISPgenerates ample amounts of these reactive fragments on the surface.CRISP also has the advantage that free reactive radical species are notactually generated. Instead, catalyzing reactants react in a continuous,non-saturating catalyzing reaction to generate adsorbate atomic ormolecular fragments, which are capable of self-elimination byrecombination when the surface has reached a passivation point. Apassivation point is specific for a specific process and is, forexample, the point of clean and hydrogen-terminated surface ofsemiconductor when a CRISP method is utilized to remove native oxide,carbon, and some metallic impurities from a semiconductor surface. ACRISP stage does not actually generate free radical species. Also,controlling the ratios of catalyzing reactants provides flexible controlof CRISP catalyzing reactions and subsequent fragment-surface reactions.As a result, certain CRISP techniques are flexibly controlled to achieveactivation of metal and semiconductor surfaces without oxidizing ornitridizing the bulk of the substrate. In contrast, plasma-inducedprocesses and other processes that use atomic or radical species, aswell as activation processes performed in liquids, typically causeundesired reactions in the bulk of the substrate.

A CRISP method in accordance with the invention is useful in a varietyof various surface treatment processes. A surface preparation methodhaving a saturating CRISP includes introducing a plurality of catalyzingreactants into a reaction chamber containing a substrate with a surface,in which the catalyzing reactants react in a continuous andnon-saturating catalyzing reaction, the catalyzing reaction generates avolatile by-product and an intermediate reactive molecular fragment, andthe intermediate reactive molecular fragment reacts with the surface ina substantially saturating fragment-surface reaction. The CRISP stage ina surface preparation method generally includes introducing a firstcatalyzing reactant into the reaction chamber, and introducing a secondcatalyzing reactant into the reaction chamber.

A CRISP method is also utilized in a process for cleaning asemiconductor surface. An example of a CRISP cleaning method includesexposing the surface to a hydride/fluoride mixture of catalyzingreactants to generate hydrogen adsorbate on the surface, which hydrogenadsorbate volatilizes an atom on the surface. Typically, the volatilizedsurface atom is from a group including O, N, C, Sn, and Al on thesurface. Typically, the substrate comprises silicon or germanium and anative oxide or nitride film is removed, and silicon or germanium fromthe oxide or nitride films is volatilized as SiH₄ or GeH₄, whereby thesurface is smoothed and becomes terminated with hydrogen. Examples ofcombinations of catalyzing reactants for substrate cleaning includeSiH₄/F₂, B₂H₆/F₂, Si₂H₆/F₂, SiH₂Cl₂/F₂, PH₃/F₂, SiH₄/ClF₃, B₂H₆/ClF₃,Si₂H₆/ClF₃, SiH₂Cl₂/ClF₃, PH₃/ClF₃, SiH₄/HF, B₂H₆/HF, Si₂H₆/HF,SiH₂Cl₂/HF, and PH₃/HF. In another aspect, in a CRISP cleaning process,the substrate typically contains a contamination atom, and thefragment-surface reaction generates a volatile surface by-productmolecule containing the contamination atom, thereby removing thecontamination atom from the surface. Frequently, the substrate containsmetallic contamination, and the fragment-surface reaction generates avolatile surface by-product molecule containing the metalliccontamination, thereby removing the metallic contamination from thesurface. In another aspect, the intermediate reactive molecular fragmentterminates the surface after the fragment-surface reaction of a cleaningmethod. In another aspect, the fragment-surface reaction saturates whenthe surface no longer contains contamination atoms.

In certain embodiments, a surface preparation method utilizing CRISPincludes: introducing a first plurality of the catalyzing reactants,which react in a first continuous and non-saturating catalyzing reactionunder a first set of reaction conditions that generates a first volatileby-product and a first intermediate reactive molecular fragment. Inanother aspect, the first intermediate reactive molecular fragment thenreacts with the surface in a first fragment-surface reaction thatgenerates a volatile surface by-product molecule containing acontamination atom, thereby removing the contamination atom from thesurface. The method then includes introducing a second plurality of thecatalyzing reactants, which react in a second continuous andnon-saturating catalyzing reaction under a second set of reactionconditions that generates a second volatile by-product and a secondintermediate reactive molecular fragment, and the second intermediatereactive molecular fragment reacts with the surface in a secondfragment-surface reaction, thereby terminating the surface. In anotheraspect, removing the contamination atom and the terminating of thesurface are conducted beyond saturation. Frequently, the contaminationatom comprises an atom selected from a group including Al, Si, O, N, S,Se, and Sn. In another aspect, the substrate in a cleaning process isterminated by an intermediate reactive molecular fragment selected froma group including OH, NH, NH₂, SH, SeH, AsH, and AsH₂.

A CRISP method in a surface preparation of process is also utilized forinitiating ALD growth by introducing a metal ALD precursor into thereaction chamber, in which the metal ALD precursor reacts with thesurface terminated with an intermediate reactive molecular fragment.

The intermediate reactive molecular fragment in a surface preparationprocess frequently comprises atomic hydrogen. In addition, thecatalyzing reaction frequently generates a plurality of intermediatereactive molecular fragments, typically comprising a hydrogen atom andmolecular fragments selected from a group including OH, NH, NH₂, SH,SeH, AsH, and AsH₂. Similar to ALD CRISP methods, controlling a flowrate ratio of the catalyzing reactants into the reaction chamber servesto control relative surface concentrations of the hydrogen atoms and themolecular fragments. Examples of CRISP surface preparation processesinclude a first type of catalyzing reactants and a second type ofcatalyzing reactants, the catalyzing reactants including a firstreactant type selected from a group including O₃, F₂, NF₃, ClF₃, HF,F₂O, FI, FNO, N₂F₂, F₂O₂, and F₄N₂, and a second reactant type selectedfrom a group including CH₄, CN, C₂H₈N₂, CH₅N, CH₆N₂, C₂H₂, C₂H₃N, C₂H₄,C₂H₄S, C₂H₅N, C₂H₆S, C₂H₆S₂, C₃H₆S, SiH₄, B₂H₆, Si₂H₆, SiH₂Cl₂, and PH₃.

Hydrogen-generating CRISP techniques using catalyzing-reactantcombinations such as SiH₄/F₂, B₂H₆/F₂, or PH₃/F₂ are also useful forremoving residual oxygen, nitrogen, carbon, tin, lead, aluminum, sulfur,selenium, and other elements that have volatile hydrides from a surfaceof a semiconductor. Silicon native oxide films are effectively removedby, for example, PH₃/F₂ CRISP at high PH₃:F₂ ratios to generate volatilePF₃O, SiF₄, H₂O, and SiH₄, which efficiently remove the native oxide.SiH₄/F₂ CRISP is milder and is used to remove residual oxygen, nitrogen,carbon, tin, aluminum, sulfur, selenium, and other elements that havevolatile hydrides. When controlled at a high SiH₄/F₂ ratio, this CRISPis capable of cleaning and smoothing silicon surfaces and terminatingthese surfaces with hydrogen.

Metallic surfaces, such as Fe—Ni or Fe—Co magnetic alloys, Ta, TaN_(x),W, WN_(x), Cu, Ti, and TiN, are cleaned to remove native oxides byexposure to PH₃/F₂ CRISP or other hydride/fluoride CRISP recipes.

Precise control over the coverage of reactive adsorbates and the abilityto produce and control different types of reactive adsorbates make CRISPan ideal tool for surface activation. Surfaces of metals,semiconductors, oxides, nitrides, sulfides, and others are terminatedwith OH, NH, NH₂, SH, SeH, AsH, and other fragments, and combinations ofthese terminations at well-controlled surface concentrations aretailored by using CRISP. For example, in an exemplary embodiment,silicon surfaces are terminated by a combination of H, OH, NH, and NH₂by conducting a CRISP stage with catalyzing reactants SiH₄, F₂O, andNF₃. Alternatively, a CRISP method utilizing catalyzing reactants SiH₄,SiCl₄, and NF₃ is useful for generating a substrate surface comprisingH, Cl, NH, and NH₂ surface species, of which the surface chlorine atomsare typically subsequently converted to OH species upon short exposureof the surface to H₂O. In another exemplary method including CRISP,magnetic alloy surfaces, such as Ni—Fe, are terminated with H, NH, andNH₂ using catalyzing reactants B₂H₆ and NF₃ in a CRISP technique thatavoids exposing these sensitive alloys to oxidizing conditions. Similarto the approach described above with reference to FIG. 1, magnetic alloysurfaces are optionally protected by an ultrathin nitride film prior tothe deposition of oxide dielectric to provide an oxide-free interface.

A dry etching method including a CRISP method includes introducing aplurality of catalyzing reactants into a reaction chamber containing asubstrate, in which the catalyzing reactants react in a continuous andnon-saturating catalyzing reaction that generates a volatile by-productand an intermediate reactive molecular fragment. In another aspect, in adry etching method, the intermediate reactive molecular fragment reactswith the substrate in a fragment-substrate reaction that generates avolatile molecular species, thereby etching the substrate. A dry etchingmethod including CRISP further includes controlling substratetemperature to control the etching. A further embodiment includesapplying an energy-containing beam to the substrate to facilitateanisotropic etching, the energy-containing beam being selected from agroup including an ion beam and an atomic beam. In one aspect, theintermediate reactive molecular fragment in an etching method comprisesatomic hydrogen. In other embodiments, the catalyzing reaction generatesa plurality of intermediate reactive molecular fragments. In stillanother aspect, the intermediate reactive molecular fragments comprisehydrogen atoms and molecular fragments selected from a group includingCl, Br, I, OH, NH, NH₂, SH, SeH, AsH, and AsH₂. In another aspect, a dryetching method further includes controlling a flow rate ratio of thecatalyzing reactants into the reaction chamber to control relativesurface concentrations of the hydrogen atoms and the molecularfragments. In another aspect, a plurality of catalyzing reactantsinclude a first type of catalyzing reactant selected from a groupincluding O₃, F₂, NF₃, ClF₃, HF, F₂O, FI, FNO, N₂F₂, F₂O₂, and F₄N₂, anda second type of catalyzing reactant selected from a group includingCH₄, CN, C₂H₈N₂, CH₅N, CH₆N₂, C₂H₂, C₂H₃N, C₂H₄, C₂H₄S, C₂H₅N, C₂H₆S,C₂H₆S₂, C₃H₆S, SiH₄, B₂H₆, Si₂H₆, SiH₂Cl₂, and PH₃. In certainembodiments, a dry etching method including CRISP is conducted to etch asolid deposit from the internal surfaces of a chemical processingapparatus.

In other embodiments of a dry etching from a process using CRISP, thesubstrate being etched comprises a solid chemical source of a chemicalprocess system. In a common embodiment, the solid chemical source is ametallic target located in a chemical source chamber upstream from anALD deposition chamber. In one aspect, varying a flow rate of at leastone catalyzing reactant into the chemical source chamber causes thecatalyzing reaction to proceed during a chemical delivery time, and thecatalyzing reaction substantially ceases during a non-delivery time. Inanother aspect, the catalyzing reaction generates the intermediatereactive molecular fragment during the chemical delivery time, and theintermediate reactive molecular fragment reacts with the metallic targetto generate the volatile molecular species during the chemical deliverytime. In another aspect, controlling a temperature of the metallictarget effects fast volatilization of the volatile molecular speciesduring the chemical delivery time, thereby generating pulse delivery ofthe volatile molecular species. In still another aspect, the volatilemolecular species comprises a metal.

CRISP is also useful for in-situ cleaning of deposition chambers andother apparatus surfaces, for example, by removing a chemical deposit,such as an Al₂O₃ or AlN film. Suitable in-situ cleaning procedures didnot exist in the prior art. Generally, such a method includesintroducing a gas mixture of catalyzing reactants, including acombination selected from a group including hydride/fluoride,hydride/fluoride/ozone/hydrocarbons, PH₃/F₂, PH₃/F₂/O₃/C₂H₂, PH₃/FCl,and PH₃/FCl/O₃/C₂H₂, and further comprises a source of chlorine selectedfrom a group including SCl₂, S₂Cl₂, ClF₃, ClF, ClI, and SiCl₄. In acertain embodiment in accordance with the invention, hydrogen-generatingCRISP effects in-situ cleaning of Al₂O₃ and AlN by volatilizing aluminumas AlH₃, and by volatilizing oxygen as H₂O or PF₃O. One of ordinaryskill in the art recognizes that there are numerous combinations ofcatalyzing reactants for achieving desired volatilization in a CRISPstage. In an exemplary embodiment, fluorine is a catalyzing reactant,and a catalyzing reactant mixture such as PH₃/F₂ or PH₃/F₂/O₃/C₂H₂generates ample amount of adsorbed hydrogen and a highly-driven surfacereaction that volatilizes oxygen as PF₃O or CO₂. Exemplaryfluorine-based reactions are represented in Equations 18-21, below.Equation 18 represents an embodiment of a process for etching Al₂O₃ inaccordance with the invention in which the volatile Al species is AlH₃:2Al₂O₃(solid)+4PH₃+6F₂→4AlH₃(volatile)+4PF₃O(volatile)+O₂.   (18)Equation 19 represents an example of etching Al₂O₃ in which the volatileAl species is AlCl₂H:2Al₂O₃(solid)+4PH₃+4ClF₃→4AlCl₂H(volatile)+4PF₃O(volatile)+2H₂O+2H₂.  (19)Equation 20 represents an additional process for etching Al₂O₃ in whichthe volatile Al species is AlH₃:Al₂O₃(solid)+2PH₃+3F₂+2O₃+C₂H₂→2AlH₃(volatile)+2PF₃O(volatile)+H₂O+2CO₂.  (20)Equation 21 represents an example of etching AlN in accordance with theinvention in which the Al volatile species is AlH₃:2AlN(solid)+2PH₃+3F₂→2AlH₃(volatile)+2PF₃(volatile)+N₂.   (21)Chlorine is also useful as one of the catalyzing reactants in a CRISPin-situ cleaning procedure. In such embodiments, a chlorine containingspecies generally improves chamber cleaning efficiency by providing apath for AlCl₃ and AlCl_(p)H_(q) volatilization.

An apparatus and a method for conducting ALD using SynchronicallyModulated Flow Draw (SMFD) is described in co-owned and copending U.S.patent application Ser. No. 10/347,575, filed Jan. 17, 2003, which isincorporated by reference. An SMFD apparatus enables ALD chemical dosageand introduction of CRISP catalyzing reactants at preferred highpressure and low flow, and ALD purge at preferred low pressure and highflow. A schematic diagram of an SMFD apparatus 400 suitable forpracticing ALD including a CRISP stage in accordance with the inventionis depicted in FIG. 8. Apparatus 400 is fed by a pressure-stabilizedinert gas at source 401. This pressurized gas is distributed to theapparatus through flow restriction elements (FRE) that provide pressurestep-down when gas is flowing through them. Inert gas is suppliedthrough valve 402 and FRE 404 into showerhead (gas distribution chamber)452. In addition, chemicals in the form of chemical gas, vapor fromliquid or solid chemicals, or mixtures of vapor or gas chemicals withinert gas are maintained at well-controlled pressure at chemical inletsources, for example, source 422. The pressurized chemical source 422 isconnected to a booster container 426 through FRE 424. Booster container426 is connected through valve 428 and FRE 430 to showerhead 452. Valve431 provides a path through FRE 432 into a vacuum line to facilitatefast and efficient showerhead purge. Other metal precursor sourcessimilar to sources 422-432 optionally are similarly connected toshowerhead zone 452. Oxygen pressurized source 408 is connected throughmass flow controller (MFC) 410 into ozone generator 412. Preferably,nitrogen gas is also connected to ozone generator 412 to improve ozoneconversion efficiency, as is known in the art. Ozone is fed intoshowerhead (gas distribution chamber) 452 through valve 414 and FRE 416.Alternatively, ozone is routed into a vacuum line through valve 418 andFRE 420. Preferably, the FREs are set to provide similar flowrestriction in both paths to suppress the need for MFC response uponswitching the flow between the 414-416 paths and the 418-420 paths.

Catalyzing reactant in the form of gas, vapor from liquid or solid, ormixtures of reactant vapor or gas with or without inert gas aremaintained at well-controlled pressure at catalyzing reactant sources,for example, source 433. The pressurized chemical source 433 isconnected into a booster container 436 through FRE 434. Boostercontainer 436 is connected through valve 438 and FRE 440 to showerhead452. Valve 442 provides a path through FRE 444 into a vacuum line tofacilitate fast and efficient showerhead purge. Accordingly, themanifold formed by elements 433-444 represents a catalyzing reactantsupply system for slow flow delivery of catalyzing reactant, such asfluorine-containing NF₃, F₂, or ClF₃ molecules as used in the B₂H₆/F₂CRISP. This source may be substituted with a high flow supply system,such as manifold 448-450.

The second zone 454 of the showerhead (gas distribution chamber 454) isfed with inert gas through valve 405 and FRE 406. In addition,catalyzing reactant is introduced from a pressurized source 448 throughvalve 449 and FRE 450. Manifold 448-450 represents a delivery line forhigh flow of catalyzing reactant such as CH₄ or C₂H₈N₂ in theO₃/hydrocarbon CRISP method. For low flow of chemicals, such as SiH₄ orB₂H₆, this manifold is replaced with a low flow manifold similar tomanifold 433-444.

The exemplary CRISP method 250 for growing ZnS discussed with referenceto FIG. 5 requires three low-flow manifolds, such as the manifold formedby elements 433-444, connected to first showerhead zone 452, for thedelivery of ClF₃, F₂, and F₂O. Additionally, three low-flow manifolds(of the type described above) are connected to second showerhead zone(gas distribution chamber) 454 to effect delivery of SiH₄, SiCl₄, andH₂S. Showerhead zone 454 is supplied with inert gas through valve 405and FRE 406. This inert gas manifold is designed to provide a low flowof inert gas out of showerhead zone 454 when CRISP is not being used.For example, during dosage of metal precursor using manifold 422-432,this low flow of inert gas protects showerhead zone 454 from backflow ofmetal precursor with minimal dilution of the metal precursor. For thisreason, showerhead 454 preferably comprises an array of high aspectratio nozzles suitable for controlling low levels of gas flow.

Showerhead 452 is separated from the ALD reaction chamber 460 by anozzle array (gas-distribution FRE) 456 that provides for restricted anduniform flow from 452 to reaction chamber 460. Similarly, showerhead 454is separated from the ALD reaction chamber 460 by a nozzle array(gas-distribution FRE) 458 that provides for restricted and uniform flowfrom showerhead 454 to reaction chamber 460. The ALD volume is connectedto draw control chamber 464 through reaction-chamber FRE 462. Drawcontrol chamber 464 is connected to vacuum pump 475 through draw-controlFRE 472. Draw control chamber 464 can be fed with (typically inert) gasdirectly through line 466, draw-source shut-off valve 468, anddraw-source-FRE 470.

Preferably, CRISP is implemented using multiple gas distributionchambers. A typical dual-zone showerhead arrangement is depictedschematically in FIG. 8. Because the two showerhead zones 452 and 454function separately, the showerhead zones are indicated schematically byseparate boxes. In other words, because of their separate functionality,each zone can be conceptualized as a separate showerhead. Nevertheless,it is understood that both zones discharge into the same volume and arepreferably incorporated in an integrated unit 455, as shown in FIG. 11and discussed below. When a method comprising CRISP in accordance withthe invention is conducted using high flow rates of chemical reactants,it is generally unnecessary to supply inert gas into draw controlchamber 464. Table 1 presents the valve positions, open or closed, ofthe shut-off valves of apparatus 400, as depicted in FIG. 8, during thefour typical stages of an ALD method comprising a CRISP stage inaccordance with the invention. For example, ALD process 100 describedabove with reference to FIG. 1 for depositing Al₂O₃ by ALD using CRISPis implemented by switching valve during the four static modes of Table1.

TABLE 1 Valve ML_(x) dose Purge CRISP Deactivation 402 CLOSE OPEN CLOSECLOSE 468 OPEN CLOSE CLOSE CLOSE 428 OPEN CLOSE CLOSE CLOSE 431 CLOSEOPEN CLOSE CLOSE 414 CLOSE CLOSE OPEN CLOSE 418 OPEN OPEN CLOSE OPEN 405OPEN CLOSE CLOSE CLOSE 449 CLOSE CLOSE OPEN OPENFor growing a protective AlN layer, as in method 100 of FIG. 1, anadditional manifold 481-484, similar to 448-450, is connected toshowerhead (gas distribution chamber) 454, as depicted in FIG. 9 showingALD apparatus 480. AlN growth is effected with manifold 481-484according to the sequence valve switching in Table 1, but with valve 482actuating instead of valve 449.

Operation of an SMFD apparatus as described herein is controllable forindependent selection of desired pressure and flow rates at each mode,while completely suppressing backflow and back-diffusion, and providingsmooth transitions between the modes. Pressure 401 and FREs 404, 456,462, and 472 are set to deliver purge-gas flow rate, Q_(purge), andmaintain showerhead pressure, P_(purge) ^(SH), and ALD reaction chamberpressure, P₄₆₀ ^(purge), during a purge stage. During dosage of a metalprecursor, ML_(x), FREs 424, 430 are set to deliver chemical to theshowerhead at a much smaller flow rate, Q_(CD). This lower flow isaccompanied by lower showerhead pressure, P_(CD) ^(SH). Inert gas issupplied to draw control chamber 464 through draw-source FRE 470. Thedirect flow of draw gas into draw control chamber 464 raises thepressure in draw control chamber 464. The increased pressure at drawcontrol chamber 464 reduces the “draw” of gas from ALD reaction chamber460 to draw control chamber 464. This reduced flow out of reactionchamber 460 is optionally used for smoothly increasing the pressure inreaction chamber 460 during chemical dosage P₄₆₀ ^(CD) to provide higherchemical exposures.

In addition to four static modes, preferably a significant transientmode is designed into the initial stage of chemical dosage. Thetransient is driven by chemical flow from booster volume 426. Given timeto equilibrate when valve 428 is closed, the pressure at 426 is similar(almost equal) to the pressure at 422, P₄₂₆ ^(static)≈P₄₂₂. When valve428 is open, under steady-state conditions, the steady-state pressure at426, P₄₂₆ ^(SS), is smaller than P₄₂₂ due to the pressure gradient overFRE 424. When valve 428 is actuated to open, the pressure at boostervolume 426 transients from ˜P₄₂₂ down to the steady-state pressure, P₄₂₆^(SS). The flow from the chemical sources into showerhead 452 isdetermined by the pressure at 426 and the conductance of FRE 430.Pressure transient at 426 induces pressure transient at 452. As aresult, during the pressure transient in booster volume 426, the flowinto the chamber follows a down transient. Concurrently, gas isintroduced or flowed into draw control chamber 464 causing a pressureincrease in draw control chamber 464 that follows a transient up.Transient time is determined by the volume of 464 and the conductance ofFRE 470. During the pressure transient in 464, the flow out of chamber460 follows a transient down. Adjusting FRE 424, 430 and 470 and thevolumes of 426 and 464 enables matching of chamber 460 flow-in transientand flow-out (draw) transients to minimize chamber pressure-excursions.As detailed in U.S. patent application Ser. No. 10/347,575, filed Jan.17, 2003, chamber pressure excursions are internally smoothed by theSMFD apparatus even when transient time constants and various valveactuations are not perfectly matched and synchronized.

During the transient, showerhead 452 and reaction chamber 460 are loadedwith chemical. Initial chemical flow is typically adjusted to match theinert gas flow during purge mode. Accordingly, continuity of flow ispreserved. The showerhead and reaction chamber are quickly loaded withchemical under high flow that is characterized with the short residencetime associated with the high flow. Transient time and gas throughputare typically adjusted to complete the transient over approximately oneto two chamber residence times. Steady-state flow rates during achemical dosage stage and during a CRISP stage are typically 10 to 500times smaller than the flow rate at purge mode. Accordingly, thebuilt-in transient serves to significantly reduce chemical dosageresponse time. This reduced response time is crucial for efficient andhigh throughput ALD.

Other embodiments of SMFD including implementation of a draw gasintroduction chamber (“DGIC”) and a draw gas plenum system are describedin detail in U.S. patent application Ser. No. 10/347,575, filed Jan. 17,2003. An ALD apparatus 500 in accordance with the invention comprising aDGIC 461 is depicted in FIG. 10. DGIC 461 is proximate to reactionchamber 460 and is separated from chamber 460 through reaction-chamberFRE 462. DGIC 461 is fluidicly connected to draw control chamber 464through DGIC-FRE 463. A DGIC 461 is utilized to inhibit diffusion ofchemicals back into reaction chamber 460 from locations downstream ofchamber 460, especially when the volume of draw control chamber 464 isrelatively large. In apparatus 500, draw control gas is introduced intoDGIC 461, which has a small volume, rather than into draw controlchamber 464. Since the volume of DGIC 461 is small, the flow of drawcontrol gas through DGIC 461 into draw control chamber 464 effectivelyprevents diffusion of chemicals towards reaction chamber 460.

When a system 400, 450, 500 is switched from chemical dose mode to purgemode, the transients are much less important. The small volume ofshowerhead 452 is quickly loaded to P_(purge) ^(SH) through therelatively high conductance of FRE 404. Draw control chamber 464pressure drop is fast due to the high conductance of draw-control FRE472. There is also no reason to artificially produce transients such asin the case of the leading edge of the chemical dose mode. Accordingly,transient effects associated with OFF actuation of the chemical dose arerather minor.

The SMFD ALD apparatus overcomes the tradeoff between the need for highflow (and low pressure) during purge (to enable efficient and short timepurge), and the need for low flow (and high pressure) during chemicaldose (to enable fast reaction and high chemical utilization). If asteady pressure is desired throughout the process, the apparatus is ableto maintain practically constant process pressure while the flow ratesare modulated by more than a factor of ten. Alternatively, both pressureand flow can be modulated in order to gain even higher efficiencies forpurge and chemical dose steps without any tradeoff effects. SMFDapparati and methods achieve this desired capability by modulating thedraw (flow out of the ALD compartment) in synchronization with themodulation of flow into the ALD compartment. Other advantages of SMFDALD techniques are summarized in U.S. patent application Ser. No.10/347,575, filed Jan. 17, 2003.

Flow rates during CRISP are adapted to the nature of the catalyzingreactants. For example, O₃ finite lifetime dictates relatively high flowrates that are necessary to compensate for O₃ decay. Accordingly,chemical delivery manifolds, such as the manifold formed by elements408-420 in FIGS. 8 and 9, are utilized. Ozone delivery manifold 408-420also accommodates the preferred continuous flow mode of commercial ozonegenerators. O₂ is continuously supplied to the ozone generator 412through an MFC 410 and the flow of O₂/O₃ out of the ozone generatorflows continuously either to showerhead zone 452 through valve 414 andFRE 416 or to a vacuum line 446 through valve 418 and FRE 420. One ormore additional catalyzing reactants, for example CH₄, are supplied athigh flow from showerhead zone 454. When CRISP is performed at highflow, using the apparatus shown in FIG. 9 configured as described inTable 1, there is no need to supply inert gas into draw control chamber464. Nevertheless, in certain embodiments, the flow necessary duringhigh flow CRISP is smaller than the flow during purge, and the pressurein draw control chamber 464 is raised by flowing draw control gas into464. Frequently, the desired pressure in draw control chamber 464 duringCRISP is different than the pressure desired during non-CRISP chemicaldosage to reduce the flow during chemical dosage. To accommodatedifferent pressures in draw control chamber 464, gas pressure from 466is routed through a second draw control gas manifold as depicted in FIG.10, and a second shut-off valve 504 and a second draw-source FRE 506 aredisposed in fluid communication between draw control gas source 466 andDGIC 461, in parallel to manifold 468-470.

CRISP using stable molecules, such as in the SH₄/NF₃ process, istypically utilized with low flow to reduce utilization of chemical andexpensive abatement. While high pressures are usually not necessary dueto the high efficiency of CRISP, slow flow is implemented by increasingthe pressure in draw control chamber 464. A catalyzingfluorine-containing reactant is delivered through manifold 433-444 witha high flow leading edge and a slow steady-state flow. Similarly,manifold, 490-502 is implemented to deliver catalyzing reactant, forexample, SiH₄, into showerhead zone 454. The exemplary ALD process modesof apparatus 500 of FIG. 10 are entered in Table 2, in which “O”signifies open, and “C” signifies closed.

TABLE 2 Mode/Valve 402 468 504 428 431 438 442 496 500 405 ML_(x) dose CO C O C C C C O O Purge O C C C O C O C C C CRISP C C O C C O C O C CDeactivation C C O C C C C O C C

Dual showerhead designs are common in the art of CVD, in which separateddelivery of reactive chemicals is sometimes important, and many suitabledesigns have been used. Preferably, CRISP dual showerhead designsinclude small effective volumes and high aspect-ratio nozzles that arebest suited for SMFD applications, as described in U.S. patentapplication Ser. No. 10/347,575, filed Jan. 17, 2003. A suitable designis depicted in schematic form in FIGS. 11 and 12. FIGS. 11 and 12illustrate schematically the division of a centrosymmetric showerhead455 into two separate chambers 452 and 454. FIG. 12 depicts the gas feedlines corresponding to FREs 404, 406 and respective outlet nozzlescorresponding to FREs 456, 458.

At low temperatures, certain metal precursor reactions require highexposure to reach saturation within a practical and cost-effective stagetime of 50 msec to 250 msec. An SMFD ALD apparatus and a correspondingmethod enable high exposures of precursors without trade-offs of purgeperformance and are, therefore, well suited for methods using lowprocess-temperature. Nevertheless, increased material utilization oftenassociated with chemical dosage at high pressure often cause undesireddeposits of solid films in an ALD apparatus. As described in detail inU.S. patent application Ser. No. 10/347,575, filed Jan. 17, 2003, thedesign of an SMFD apparatus lends itself to an integrated abatementsystem. The integrated abatement is based on efficient conversion of ALDmetal precursors into a solid deposit on a specially designed insert.Integrated abatement efficiency and maintenance schedules are enhancedby the inherent low material usage of SMFD ALD methods. Nevertheless,when low temperature ALD dictates increased usage of ALD metalprecursor, a preferred design reduces undesired deposition of chemicalson apparatus surfaces.

FIG. 13 depicts schematically an apparatus 540 for conducting a methodin accordance with the invention including a high level of metalprecursors. For descriptive purposes, a low-temperature ALD methodincluding a metal-precursor dosage stage and a CRISP stage using acatalyzing reactant mixture O₃/CH₄ is discussed. For the sake ofclarity, parts of the apparatus upstream from ALD reaction chamber 460are not shown in FIG. 13. Apparatus 540 includes ALD reaction chamber460, DGIC 461, and draw control chamber 464. Draw control chamber 464 isconnected to after-draw control chamber 554 through FRE 550, and toafter-draw control chamber 558 through FRE 552 and high conductancevalve 556. After-draw control chamber 554 is connected to a vacuum pump570 through after-draw FRE 566. After-draw control chamber 558 isconnected to a vacuum pump through a high conductance valve 560 andafter-draw FRE 568. After-draw control chamber 554 is fed with(typically inert) gas through valve 572 and FRE 574. After-draw controlchamber 558 is fed with (typically inert) gas through valve 576 and FRE578. After-draw control chambers 554 and 558 may also be connected todifferent vacuum pumps (not shown). Synchronous flow-draw modulation isperformed utilizing draw-control chamber 464 in accordance with theteaching of U.S. patent application Ser. No. 10/347,575, filed Jan. 17,2003. The pressure in chambers 554 or 558 is raised selectively byflowing after-draw gas through valve 572 and FRE 574, and valve 576 andFRE 578, respectively, into these chambers to suppress flow from 464.Accordingly, the major portion of the flow can be selectively directedto either 554 or 558. After-draw control chamber 558 includes a cooledhigh surface-area insert element. Concurrent with metal precursor dosageand purge, flow out of draw control chamber 464 is diverted intoafter-draw control chamber 558, where the excess of metal precursor iscondensed and removed from the effluent. This functionality is achievedby flowing after-control gas into after-draw control chamber 554,therefore raising the pressure in 554 and diverting most of the flowinto 558.

Metal precursor collection in after-draw control chamber 558 isconducted during chemical dosage and chemical purge. During the CRISPstage, the chemicals are diverted mainly into after-draw control chamber554 by flowing after-draw control gas into after-draw control chamber558. After-draw control chamber 554 typically includes an integratedabatement system as described in a U.S. patent application Ser. No.10/347,575, filed Jan. 17, 2003. Integrated abatement elements areuseful for eliminating trace amounts of metal precursors that enter 554.Trace amounts of CRISP chemicals also enter after-draw control chamber558. Nevertheless, the temperature of the condensation element in 558 iscommonly set to condense effectively the metal precursor, while allowingthe gaseous catalyzing reactants to pass through. In addition, anoptional ozone-quenching element upstream of after-draw control chamber558 further suppresses possible reaction inside after-draw controlchamber 558. For optimized performance, the volume of draw controlchamber 464 is kept at a minimum, as described in U.S. patentapplication Ser. No. 10/347,575, filed Jan. 17, 2003. In addition, thewalls of draw control chamber 464 are lined with heatable metal sheetsthat can be removed for easy maintenance since some growth of film,mostly by ALD mode, occurs on the liners.

An exemplary ALD process for deposition of Al₂O₃ using Al(CH₃)₃ metalprecursor and a CRISP catalyzing reactant mixture O₃/CH₄ conducted attemperatures below 100° C. is next described. The Al(CH₃)₃ reactionstage is conducted at a pressure less than under 500 mTorr, using 10sccm flow. The purge of Al(CH₃)₃ is performed at 50 mTorr and 500 sccmflow. The CRISP stage is conducted at 200 mTorr pressure using 200 sccmflow. During Al(CH₃)₃ chemical dosage, a draw control gas flow of 400sccm into draw control chamber 464 keeps the pressure high in ALDreaction chamber 460, and a flow of 650 sccm into after-draw controlchamber 554 diverts most of the effluent coming from draw controlchamber 464 into after-draw control chamber 558. During the purge with500 sccm, the flow of 650 sccm into after-draw control chamber 554diverts most of the effluent coming from draw control chamber 464 intoafter-draw control chamber 558. Excess Al(CH₃)₃ is condensed on thecondensation element that is maintained at 0° C. During the CRISPprocess, a flow of 750 sccm into after-draw control chamber 558 divertsmost of the effluent coming from chamber 464 into after-draw controlchamber 554.

Condensation/after-draw control chamber 558 is cleaned by a simpleprocedure. When the metal precursor is gaseous, the procedure includesisolating after-draw control chamber 558 with conductance valves 556 and560, warming up the condensation element, and collecting the gas throughvalve 562. When the metal precursor is liquid, valve 562 functions as aliquid draining valve. When the metal precursor is solid at roomtemperature, valves 556 and 560 are closed, thereby releasing after-drawcontrol chamber 558 from isolation, and the chemical precursor isremoved using conventional techniques, such as solvent extraction. Theprecursor is collected and recycled (after an appropriate purification)when economically and environmentally feasible. Alternatively, alow-cost metal precursor is neutralized and disposed according toconventional techniques.

Recently, an SMFD prototype was successfully operated with zerosteady-state flow of chemical during dosage. In that embodiment,chemical dosage was accomplished by a fast booster flow to dose the ALDreaction chamber 460 with chemical. Consequentially, the flow ofchemical was stopped by shutting the chemical dosage valve 428 while thedraw control flow of gas into draw control chamber 464 was maintained.The chemical was effectively trapped for an additional zero-flow dosageperiod sufficiently long enough for effectively saturating the ALDreaction. This method of operating SMFD is desirable in the case of lowtemperature ALD in which slower precursor reaction rates are acceleratedby dosing chemicals at maximized partial pressure (up to 100% dose) tothe point that the ALD space is fully dosed, then maintaining this highchemical pressure without further flow of chemical, for as long asnecessary to complete the ALD reaction.

Table 3 summarizes the exemplary ALD cycle. The notation ML_(x) doserepresents the flow of chemical into the ALD space. The notation ML_(x)hold represents the zero-flow part of the chemical dose.

TABLE 3 Mode/Valve 402 468 504 428 431 438 442 496 500 405 ML_(x) dose CO C O C C C C O O ML_(x) hold C O C C C C C C O O Purge O C C C O C O CC C CRISP C C O C C O C O C C Deactivation C C O C C C C O C C

Optionally, a metal precursor is pulsed into showerhead zone 452 byliquid injection. For example, a pulsed valve such as the ParkerHannifin GV series 99 mounted on the top of the showerhead is used tometer small droplets of liquids into (heatable) showerhead zone 452 andcreate a very fast pressure rise. This fast pressure increase in theshowerhead creates a fast increase in pressure and flow in the ALDchamber. When accompanied with fast pressure increase in draw controlchamber 464, this technique produces significant pressure excursionsthat provide large chemical exposures within short periods of time andwith short delays. This technique is especially useful for delivery oflow vapor pressure liquid chemicals. Alternatively, a low vapor pressuresolid chemical solvated in a high vapor pressure solvent is metered andevaporated inside the showerhead. Rapid solvent evaporation is achievedthroughout the ALD reaction chamber by a delay between the onset of flow(pulsed metered liquid) and draw modulation. Downstream effluenttrapping as described above with reference to FIG. 13 is particularlycompatible with a pulsed excursion mode of chemical dosage to removelarge amounts of chemicals from exhaust effluents without adverselyaffecting vacuum performance or the environment.

Those skilled in the art appreciate that CRISP methods are useful forimproving many different processing techniques. In particular, theability to generate ample amounts of reactive atoms, molecular species,and molecular fragments on a surface circumvents the difficult, and manytimes practically impossible, need to deliver unstable reactive atomsand other chemical species to react with a substrate. One prominentproblem of the prior art is the difficulty in delivering atomic hydrogenfrom a remote space into a reaction chamber without detrimental loss dueto unavoidable surface and gas phase recombination.

Accordingly, CRISP enables cost-effective improvement of ALD dosagereactions, as discussed above. For example, adsorbed hydrogen isproduced by a catalyzing reaction CF↓+DH↓→DF↑+C↑+H(adsorbate). The arrownotations represent reactants (down) and volatile by-products (up).These types of CRISPs circumvent the difficult task of deliveringhydrogen atoms from remote locations. Most ALD of elemental metal andsemiconductor films is based on a cycle comprising dosage of metal (orsemiconductor) precursors, as a first ALD reactant, and hydrogen orstrongly reducing chemicals as the second ALD reactant. As explainedabove, plasma-generated atomic hydrogen is often incompatible withcost-effective ALD. Strongly reducing molecules, such as SiH₄, Si₂H₆,and B₂H₆, have been unstable in prior-art ALD process temperaturesleading to mixed ALD-CVD deposition-mode. In contrast, CRISP methodsimprove ALD of compound films by replacing the non-metal containingprecursors with more reactive CRISPs. For example, a conventional CHreactant is replaced with C and H adsorbates according to the process:CF↓+DH↓→DF↑+C(adsorbate)+H(adsorbate).

CRISP also improves CVD. CVD reactions are enhanced by the replacementof conventional CVD reactants with CRISP equivalents. For example, H₂molecules that are used to reduce WF₆ in the W CVD process aresubstituted with CRISP-generated hydrogen adsorbates to enhance thedeposition rate and/or reduce process temperature and to improve filmquality (by, for example, reducing fluorine levels). Similarly, copperCVD from Cu(tfac)₂ is enhanced by the substitution of H₂ withCRISP-generated adsorbed hydrogen.

A CVD method including a CRISP method in accordance with the inventionincludes introducing a CVD reactant into a reaction chamber containingthe substrate, introducing a plurality of catalyzing reactants into thereaction chamber, whereby the catalyzing reactants react in a continuousand non-saturating catalyzing reaction that generates a volatileby-product molecule and an intermediate reactive molecular fragment at asubstrate surface, and the intermediate reactive molecular fragmentreacts with the CVD reactant in a CVD reaction that deposits a solidfilm on the surface. Typically, the catalyzing reaction is more than 10times faster than the CVD reaction. Also, the CVD reaction including theintermediate reactive molecular fragment and the CVD reactant istypically more than 10 times faster than a reaction including theunreacted catalyzing reactants and the CVD reactant. In certain CVDreactions involving CRISP, the intermediate reactive molecular fragmentcomprises atomic hydrogen. In an example of a CVD CRISP process, the CVDreactant comprises WF₆ and the deposited solid film comprises W. Inanother example, the CVD reactant comprises a copper (II)beta-diketonate complex and the solid film comprises copper. In anotherexample, the copper (II) beta-diketonate complex comprises Cu(tfac)₂.

In another aspect of a CVD CRISP process, the catalyzing reactiongenerates a plurality of intermediate reactive molecular fragments. Inanother aspect, molecular fragments comprise a hydrogen atom and anothermolecular fragment selected from a group including OH, NH, NH₂, SH, SeH,AsH, and AsH₂. In another aspect, controlling a flow ratio of thecatalyzing reactants serves to control relative surface concentrationsof the intermediate reactive molecular fragments, typically hydrogenatoms and other molecular fragments. In an example of a CVD CRISPprocess, the CVD reactant comprises a copper (II) beta-diketonatecomplex, the solid film comprises copper, and the molecular fragmentscomprise OH. In particular embodiments, the copper (II) beta-diketonatecomplex comprises Cu(hfac)₂. In another example, the CVD reactantcomprises tetraethoxysilane (TEOS) and the molecular fragment comprisesOH. In other examples of CVD CRISP processes, a plurality of catalyzingreactants comprise a first type of catalyzing reactants and a secondtype of catalyzing reactants, a first-type catalyzing reactant isselected from a group including O₃, F₂, NF₃, ClF₃, HF, F₂O, FI, FNO,N₂F₂, F₂O₂, and F₄N₂; and a second-type catalyzing reactant is selectedfrom a group including CH₄, CN, C₂H₈N₂, CH₅N, CH₆N₂, C₂H₂, C₂H₃N, C₂H₄,C₂H₄S, C₂H₅N, C₂H₆S, C₂H₆S₂, C₃H₆S, SiH₄, B₂H₆, Si₂H₆, SiH₂Cl₂, and PH₃.

In another embodiment of a CVD CRISP process, CRISP also improvesabatement techniques. A CVD reactant is introduced into an abatementreaction chamber from a chemical reaction chamber and the catalyzingreactants are introduced independently into the abatement reactionchamber, and the catalyzing reaction generates an intermediate reactivemolecular fragment that reacts with the CVD reactant to facilitateabatement. In certain embodiments, the abatement is conducted at atemperature not exceeding 150° C. In one example, the CVD reactantcomprises TEOS. In another example, the CVD reactant comprises WF₆. Instill another example, the CVD reactant comprises a copper (II)beta-diketonate. In still another example, the CVD reactant comprisesAlCl₃. For example, tetraethoxysilane (TEOS, Si(OC₂O₅)₄) reacts atsubatmospheric pressure (prior to the pump) or atmospheric pressure(pump-exhaust) with CRISP-generated hydrogen and oxygen adsorbates.Copper and tungsten precursors are also effectively abated at lowertemperatures by the CVD processes mentioned above.

Etch technology utilizes remotely-generated ion or atomic beams withCRISP-generated reactive adsorbate fragments. For example, aluminumetching is facilitated by CRISP-generated chlorine resulting from acatalyzing reaction involving a SiCl₄/ClF₃ mixture, or similar mixture.Alternatively, chlorine is generated in a catalyzing reaction of CCl₄and O₃ (volatile CO₂ drives the catalyzing reaction). Additional etchingspecies, such as Br and I, are similarly generated in a catalyzingreaction of halocarbon molecules and O₃. As described above, CRISP isuseful for cleaning oxygen, carbon, and metallic impurities fromsubstrate wafers and from apparatus walls.

CRISP is also useful in film treatments, such as in a process equivalentto a “forming gas anneal”. In such a process, CRISP generates a highconcentration of atomic and/or activated hydrogen at a surface of agrown film to facilitate more efficient and lower temperature reductionof interface defects. CRISP-generated hydrogen adsorbate therebyreplaces conventionally used H₂-gas. For example, a clean silicon orcompound semiconductor surface is smoothed by providing ampleconcentration of intermediate reactive molecular-fragment hydrogen atthe surface of a mildly annealed substrate to induce step and kinkmigration and coalescence.

CRISP enables annealing of integrated circuit substrates faster or at alower temperature than the prior art. The ambient effect is enhancedbecause CRISP provides more reactive species on the surface of a heatedsubstrate. For example, H₂O in an anneal is replaced by a catalyzingreaction involving an O₃/hydrocarbon mixture, which generates molecularhydrogen and oxygen adsorbate fragments in their most reactive form.

CRISP is also useful for providing reactive dopants, such as B or P, ona surface in an atomic adsorbed form. Accordingly, very shallow dopedareas may be realized. A relatively simple mask of oxide sufficientlycontains the shallow doping into exposed, etched windows.

CRISP is useful for promoting hetero-epitaxial growth of thin strainedlayers. For example, an exposed silicon area is converted into a Si—Gethin layer by utilizing CRISP to generate ample concentrations ofreactive Ge and H adsorbed on the surface, such as from exposure to GeH₄and ClF₃ (or other fluorine containing CRISP reactants) at a relativelyhigh GeH₄:ClF₃ ratio to promote generation of adsorbed H,GeH_(p)Cl_(q)F_(r), and volatile GeF₄ and SiF₄. This treatment obtains avery thin layer of epitaxial Si—Ge, for example, in the area of a gatechannel.

In another extension of CRISP, CRISP functions as a “point of use”chemical source. For example, ALD and CVD processes are conducted usingCRISP processes designed to induce etch processes on a surface of ametallic or compound target. This enables high flow delivery ofnon-volatile precursors and metastable precursors, as well as thegeneration of a pure precursor flow when commercially availablechemicals are not sufficiently pure. For example, CuCl or Cu₃Cl₃ vaporsrequire temperatures in excess of 200° C. to sustain adequate vaporpressure and flow. As a result, in the prior art, chemical delivery isdifficult and impractical, especially when fast flow-switching isnecessary to conduct ALD. Through CRISP, however, this problem iscircumvented. By reacting CRISP catalyzing reactants, such as SiCl₄ andClF₃, to react in a fluorine-generating catalyzing reaction in thepresence of a metallic Cu-target maintained at high temperature in areaction space upstream from the deposition chamber, CuCl delivery isobtained. Such CRISP catalyzing reactants are convenient gaseouschemicals, suitable for steady-state delivery and fast switching.

Systems, apparati, and methods designed and operated to use CRISP inaccordance with the invention are particularly useful in ALD technology.Catalytic reactions for induced surface process (CRISP) is also useful,however, in a wide variety of circumstances and applications. It isevident that those skilled in the art may now make numerous uses andmodifications of the specific embodiments described, without departingfrom the inventive concepts. It is also evident that the steps recitedmay, in some instances, be performed in a different order; or equivalentstructures and processes may be substituted for the structures andprocesses described. Since certain changes may be made in the abovesystems and methods without departing from the scope of the invention,it is intended that all subject matter contained in the abovedescription or shown in the accompanying drawings be interpreted asillustrative and not in a limiting sense. Consequently, the invention isto be construed as embracing each and every novel feature and novelcombination of features present in or inherently possessed by thesystems, devices, and methods described in the claims below and by theirequivalents.

1. A method for cleaning a semiconductor surface comprising exposingsaid surface to a hydride/fluoride mixture of catalyzing reactants togenerate hydrogen adsorbate on the surface to volatilize an atomselected from the group consisting of O, N, C, Sn, and Al from saidsurface: wherein said catalyzing reactants react in a catalyzingreaction which consumes said hydride/fluoride mixture of catalyzingreactants; said catalyzing reaction is continuous and non-saturating;said catalyzing reaction generates a volatile by-product and anintermediate reactive hydrogen adsorbate on said surface; and saidintermediate hydrogen adsorbate reacts with said atom in afragment-surface reaction.
 2. A method as in claim 1 wherein saidsubstrate comprises silicon or germanium and wherein a native oxide ornitride film is removed, and silicon or germanium from said oxide ornitride films is volatilized as SiH₄ or GeH₄, and said surface isthereby smoothed and becomes terminated with hydrogen.
 3. A method as inclaim 1 wherein said mixture of catalyzing reactants is selected fromthe group consisting of SiH₄/F₂, B₂H₆/F₂, Si₂H₆/F₂, SiH₂Cl₂/F₂, PH₃/F₂,SiH₄/ClF₃, B₂H₆/ClF₃, Si₂H₆/ClF₃, SiH₂Cl₂/ClF₃, PH₃/ClF₃, SiH₄/HF,B₂H₆/HF, Si₂H₆/HF, SiH₂Cl₂/HF, and PH₃/HF.